National statistics

Background Quality Report

Updated 21 September 2023

1. Contact

• Organisation unit - Knowledge, Analysis and Intelligence (KAI)
• Name - N Yates
• Function - Statistician, Direct Business Taxes
• Mail address - Floor 4, India Buildings, 31 Water Street, Liverpool, L2 0RD
• Email - ct.statistics@hmrc.gov.uk

2. Statistical presentation

2.1 Data description

This publication provides a breakdown of Corporation Tax (CT) receipts and liabilities by number of companies, income, allowances, deductions, industry sector, size and financial year. It includes the CT, Bank Levy, Bank Surcharge, Residential Property Developer Tax (RPDT), and Energy Profits Levy (EPL) receipts figures by financial year, based on the account period end date of companies.

When a company submits a Corporation Tax return to HMRC with details of their taxable profits for their year and the amount of tax that needs to be paid, the amount of tax to be paid is known as their ‘liability’. When a company makes a payment to HMRC in relation to their Corporation Tax for any tax year, these are known as ‘receipts’.

This publication only includes figures for previous years. Forecasts of future CT receipts are produced and published by the Office for Budget Responsibility, and can be found on their website.

2.2 Classification system

Breakdowns of number of companies, income, tax liabilities, allowances and deductions are determined based on data submitted by companies on their Corporation Tax return.

A unique taxpayer reference number, assigned to each registered company, is used to aggregate the data.

Industrial sector is categorised in two ways:

1. UK Standard Industrial Classification (SIC) 2007.
2. Summary Trade Classification (STC) codes.

2.3 Sector coverage

Corporation Tax is a direct tax charged on the profits made by companies, public corporations and unincorporated associations such as industrial and provident societies, clubs and trade associations. Companies operating in all industry sectors are required to pay Corporation Tax.

2.4 Statistical concepts and definitions

Corporation Tax receipts

The amount of CT collected by HMRC.

Corporation Tax liabilities

The amount of CT that companies must pay to HMRC. CT liabilities are considered to be accrued in the financial year where the end date of the company’s accounting period lands.

Financial year

The statistics are aggregated into financial years. A financial year stretches from 1st April until 31st March the following calendar year.

Number of companies

The number of companies who have registered with HMRC and are required to submit a CT600 Corporation Tax return, in a given financial year. Most tables in the analysis only include companies who have a positive CT liability.

Company profit and deductions

For CT purposes, a company’s profits comprise its income and capital gains. This includes trading profits, investments and selling assets for more than they cost.

Capital allowances can be claimed against profits to reduce taxable income.

Losses occurring in-year, brought forward from previous years and carried back are also set against profits. Other allowable deductions and group relief are then subtracted, to obtain profits chargeable to CT.

Tax rates

From 1 April 2015 to 31 March 2023, there was a unified rate of CT rather than separate main and small profits rates. On 1 April 2015 the rate was set at 20% and reduced to 19% on 1 April 2017.

From 1 April 2023 the Corporation Tax main rate for non-ring fence profits is 25% for profits above £250,000, with a small profits rate of 19% for companies with profits of £50,000 or less.

Companies with profits between £50,000 and £250,000 will pay tax at the main rate, reduced by a marginal relief. Further information on Corporation Tax rates can be found on GOV.UK.

Different tax rates apply to companies with income and gains from oil and gas and gas extraction or oil rights, known as ‘ring-fence’ companies. These companies are also subject to a supplementary tax charge on their ring-fenced profits.

A special tax rate applies to unit trusts and open-ended investment companies.

Capital allowances

Capital allowances can be claimed when companies buy assets that they keep to use in the business, for example equipment machinery, business vehicles, cars, vans or lorries.

The value of the item is deducted from profits before tax is paid.

As well as plant and machinery, capital allowances can also be claimed for renovating business premises; research and development; intellectual property; patents; extracting minerals; and structure and buildings.

Further information can be found on the Claim capital allowances webpage of GOV.UK.

Quarterly Instalment Payments

Since 1999, large companies have been required to pay their CT by quarterly instalments. More information about this new regime can be found on the information for large companies section on the GOV.UK website.

Bank Surcharge

The Bank Surcharge applies to all banking companies and building societies within the scope of the charge and was introduced in The Finance Act (No 2) 2015 to levy a surcharge on the profits of banking companies from 1 January 2016.

The Bank Corporation Tax Surcharge page of the GOV.UK website, provides further information.

Bank Levy

An annual charge based on the equity and liabilities reported in year-end balance sheets, for periods of account ending on or after 1 January 2011. The Bank Levy applies to the following:

• UK banks, banking groups and building societies
• Foreign banking groups operating in the UK through permanent establishments or subsidiaries
• UK banks and banking sub-groups in non-banking groups

No charge arises on the first £20 billion of chargeable equity and liabilities of the relevant period, which in practice means that only banks with a large operating presence in the UK pay the Bank Levy.

More information can be found on the Bank Levy webpage of GOV.UK.

Offshore Corporation Tax/ Ring-Fence Corporation Tax

Companies involved in the exploration for, and production of, oil and gas in the UK and on the UK Continental Shelf (UKCS) are liable for Offshore CT, which is comprised of Ring-Fence Corporation Tax (RFCT) and the Supplementary Charge (SC). Collectively, these are known as ring-fenced oil and gas companies.

Further information can be found at the Oil and gas: Ring Fence Corporation Tax web page of the GOV.UK website.

Energy Profits Levy (EPL)

The Energy Profits Levy is an additional tax on UK oil and gas profits on top of the existing RFCT and SC. The Levy has effect for profits arising on or after 26 May 2022.

More information can be found on the Energy (Oil and Gas) Profits Levy webpage of GOV.UK.

Residential Property Developer Tax (RPDT)

The RPDT is a 4% tax applied to the largest residential property developers on the profits they make on UK residential property development. The RPDT is applied to profits made from 1 April 2022.

Further information can be found on the Residential Property Developer Tax webpage of GOV.UK.

2.5 Statistical unit

The unit in the statistics is companies and other entities required to pay Corporation Tax.

2.6 Statistical population

All businesses liable to pay Corporation Tax in the UK. This includes UK limited companies; any foreign company with a UK branch or office; and clubs, co-operatives or other unincorporated associations, for example community groups or sports clubs.

2.7 Reference area

The geographic region covered by the data is the United Kingdom (UK).

2.8 Time coverage

For receipts, the statistics cover the period from financial year 2013 to 2014 until the end of financial year 2022 to 2023.

For liabilities, the statistics cover the period from financial year 2016 to 2017 until the latest financial year for which a complete set of CT returns is available. For the most recent publication that is accounting periods that ended during financial year 2021 to 2022.

3. Statistical processing

3.1 Source data

Receipts

The data for CT, Bank Surcharge and Bank Levy receipts comes mainly from payments recorded on the HMRC COTAX administrative system.

The CT receipts analysis includes breakdowns by industrial sectors and the classification is based on the UK Standard Industrial Classification (SIC) 2007.

Companies do not report their SIC 2007 sector to HMRC as part of their CT return or registration, so they have been assigned to a sector based on data from external sources; this is predominantly matching records to Companies House Free Data Product and the Office for National Statistics’ (ONS) Inter-Departmental Business Register (IDBR) survey.

Some categories have been combined in order to protect taxpayer confidentiality. Some SIC codes have been estimated where receipts payments have been made through a Group Payment Arrangement.

The data for RPDT and EPL receipts comes from payments recorded on the COTAX administration system alongside other operational HMRC data.

Liabilities

The data for CT liabilities comes from CT assessments and returns as recorded on the HMRC COTAX administrative system. Data from 100% of companies is used.

The available data for each company is as recorded on the Company Tax Return (CT600) form, including any modifications or additions made in subsequent assessments. The CT600 form contains a systematic record of the company’s CT calculations, starting with its income and chargeable gains and considering any relevant deductions and reliefs.

The CT liabilities analysis includes breakdowns by industrial sectors and the classification is based on the UK Standard Industrial Classification (SIC) 2007. SIC codes have been assigned to companies using a similar methodology to the CT receipts data described above.

The CT liabilities and receipts analysis also includes a breakdown by high-level Summary Trade Classification (STC). These are historical 2-digit codes used by HMRC to classify companies by their type of business activity. This classification is based on the Standard Industrial Classification SIC (92).

The CT liabilities analysis additionally includes a breakdown by estimated small and medium-sized enterprise (SME) status. The criteria used to determine a company’s SME status are employees, assets and turnover. These values are considered at group level and as defined by the Companies Act definition of SME.

Not all of the information required to estimate a company’s SME status is collected by HMRC as part of CT returns and registrations, and so external data is also used from the IDBR and information provided by companies to Companies House and accessed through Bureau Van Dijk’s Financial Analysis Made Easy (FAME) product.

Companies with insufficient data to make an accurate estimate, are classified as ‘Unknown’, and are more likely to be ‘Micro’ or ‘Small’ due to lesser requirements to submit detailed information to Companies House.

3.2 Frequency of data collection

The data for CT receipts and Bank Levy receipts are downloaded every night into databases for analysis the following day.

The data for CT liabilities is compiled on an annual basis.

3.3 Data collection

Data on Corporation Tax receipts and liabilities is sourced from the HMRC COTAX administrative system.

Liabilities data are acquired by HMRC when a company submits a completed CT600 Company Tax Return. The majority are submitted electronically in the iXBRL format which feeds directly into the COTAX system. COTAX detects calculation errors in real time in the tax return, and displays messages on the user’s screen.

Receipts data are acquired when a company makes a Corporation Tax payment. All payments are made to HMRC electronically through either online or telephone banking; CHAPS; Bacs; Direct Debit; online by debit or corporate credit card; or at a bank or building society. A record of a company’s payment is captured in the COTAX system.

3.4 Data validation

Checks carried out on the data include:

• Automated checks take place when loading data into the analysis database. Inconsistencies are automatically ‘repaired’ if possible; otherwise the record is flagged as invalid.
• Analysts check that the number of records loaded into the analysis database is as expected.
• Reports are run showing the cases with the largest profits and losses. These are examined individually. Records deemed to be incorrect are adjusted in the analysis database.
• Any large changes in receipts or liabilities figures from one statistical release to the next are investigated.
• Total CT receipts figures are checked for consistency with the latest HMRC financial outturn position.

3.5 Data compilation

Aggregating data

Data are aggregated using a unique taxpayer reference number assigned to each company. This unique number does not change across financial years.

4. Quality Management

4.1 Quality assurance

All official statistics produced by KAI, must meet the standards in the Code of Practice for Statistics produced by the UK Statistics Authority and all analysts adhere to best practice as set out in the ‘Quality’ pillar.

Analytical Quality Assurance describes the arrangements and procedures put in place to ensure analytical outputs are error free and fit-for-purpose. It is an essential part of KAI’s way of working as the complexity of our work and the speed at which we are asked to provide advice means there is a high risk of error which can have serious consequences on KAI’s and HMRC’s reputation, decisions, and in turn on peoples’ lives.

Every piece of analysis is unique, and as a result there is no single quality assurance (QA) checklist that contains all the QA tasks needed for every project. Nonetheless, analysts in KAI use a checklist that summarises the key QA tasks, and is used as a starting point for teams when they are considering what QA actions to undertake.

Teams amend and adapt it as they see fit, to take account of the level of risk associated with their analysis, and the different QA tasks that are relevant to the work.

At the start of a project, during the planning stage, analysts and managers make a risk-based decision on what level of QA is required.

Analysts and managers construct a plan for all the QA tasks that will need to be completed, along with documentation on how each of those tasks are to be carried out, and turn this list into a QA checklist specific to the project.

Analysts carry out the QA tasks, update the checklist, and pass onto the Senior Responsible Officer for review and eventual sign off.

Review of SIC classifications of companies in 2022 and 2023

In the 2023 publication there have been significant revisions to previously published estimates of the number of companies and total CT liabilities by SIC section and division. This is due an improved methodology used from 2023.

As explained further above, companies do not report their SIC 2007 sector to HMRC as part of their CT return or registration, so they have been assigned to a sector based on data from external sources and available to HMRC analysts; this is predominantly matching records to Companies House Free Data Product (FDP) and the Office for National Statistics’ (ONS) Inter-Departmental Business Register (IDBR) survey. From 2023 onwards HMRC have switched from using the IDBR to the FDP as the preferred matching method, and IDBR has now only been used where no match exists within the FDP.

During a review of the methodology, analysts found the FDP to be a more reliable source as it matches the declaration of SIC by the company to Companies House (which is publicly available) for the reporting year. The IDBR can sometimes indicate the SIC of the parent company for those companies within groups; this is due to the slightly different reporting units used within the IDBR.

The improved methodology has been used from 2023 for figures showing the numbers of companies and CT liability by SIC and applied across all financial years between 2016 to 2017 and 2021 to 2022 in order to maintain comparability between years. This has, however, led to significant revisions from previously published figures in the 2022 and earlier publications, particularly in the ‘Mining and Quarrying’, ‘Professional, Scientific and Technical’ and ‘Admin and Support Services’ SIC sections. The improved methodology has also reduced the number of ‘Unclassified’ companies with unknown SIC compared with previous years.

Previous review of methodology and data in 2021/2022

As part of HMRC’s commitment to improve the quality of its National Statistics products, and to act on recommendations set out in the review carried out by the Office for Statistics Regulation (OSR), a thorough review of the CT data and methodology to produce the publication was carried out during 2021 and 2022.

As part of this review, analysts spent time gaining a deeper understanding of the ‘data journey’ from collection to publication, working with suppliers and experts to improve knowledge of the data collection process.

Analysts considered the impact of changes to the CT forms and the flow of data from within HMRC systems to the analytical databases used to produce the publication.

Analysts also revised the complex coding and methodology used to produce the statistics, improving accuracy, efficiency and transparency of the process.

The review identified some areas where the accuracy could be enhanced using new and existing data sources and has enabled new analyses of CT. Consequently, in the 2022 publication there were some revisions to previously released figures that have been made as a result of these methodological changes; these are in addition to the changes in the raw data that are seen every year (for example, revisions made by companies for previous years’ returns).

This is particularly relevant for the statistics on Capital Allowances where the review has led to significant revisions to the figures compared with previous years’ publication and has enabled a more detailed breakdown of this data to meet user demand.

4.2 Quality assessment

The QA for this project adhered to the framework described in ‘4.1 Quality assurance’ and the specific procedures undertaken were as follows:

Stage 1 – Specifying the question

Up to date documentation was agreed with stakeholders setting out outputs needed and by when; how the outputs will be used; and all the parameters required for the analysis.

Stage 2 – Developing the methodology

Methodology was agreed and developed in collaboration with stakeholders and others with relevant expertise, ensuring it was fit for purpose and would deliver the required outputs.

Stage 3 – Building and populating a model/piece of code

• Analysis was produced using the most appropriate software and in line with good practice guidance.
• Data inputs were checked to ensure they were fit-for-purpose by reviewing available documentation and, where possible, through direct contact with data suppliers.
• QA of the input data was carried out.
• The analysis was audited by someone other than the lead analyst – checking code and methodology.

Stage 4 – Running and testing the model/code

• Results were compared with those produced in previous years and differences understood and determined to be genuine.
• Results were compared with comparable independent estimates, and differences understood. For example, total CT receipts figures were checked for consistency with the latest HMRC financial outturn position.
• Results were determined to be explainable and in line with expectations.

Stage 5 – Drafting the final output

• Checks were completed to ensure internal consistency (e.g. totals equal the sum of the components).
• The final outputs were independently proof read and checked.

5. Relevance

5.1 User needs

This analysis is likely to be of interest to users under the following broad headings:

• national government – policy makers and MPs
• regional and local governments
• academia and research bodies
• media
• business community
• general public

5.2 User satisfaction

Formal investigations into user satisfaction have not been undertaken, however feedback from users following the release have been received and KAI are always open to ideas for new analysis to meet changing user requirements.

5.3 Completeness

It is a legal requirement that all qualifying businesses submit a CT600 Corporation Tax return, at the required time. Penalties exist for non-compliance. The statistics contained in this report can therefore be considered as complete.

6. Accuracy and reliability

6.1 Overall accuracy

This analysis is based on administrative data, and accuracy is addressed by eliminating non-sampling errors as much as possible through adherence to the quality assurance framework.

The potential sources of error include:

• Companies entering incorrect information onto the CT600 Company Tax Return form.
• Human or software error when entering the CT600 data into the COTAX system.
• Companies not completing their Company Tax Return form by the required date.
• The accuracy and consistency of the assignment of SIC 2007 and the Summary Trade Classification (STC) codes, when classifying companies by industry sector.
• Mistakes in the programming code used to analyse the data and produce the statistics, and by analysts interpreting the data incorrectly.

6.2 Sampling error

Since 2005-06, samples are no longer used to compile the analysis, instead being based on administrative data from HMRC’s COTAX system. Sampling error is therefore not relevant.

6.3 Non-sampling error

Coverage error

All qualifying businesses must register with HMRC for Corporation Tax when they start doing business, and inform HMRC when they cease trading. Coverage error is therefore not relevant.

Measurement error

The main sources of measurement error could be categorised as respondent errors and include the following:

• Companies may make errors entering their information onto the CT600 Company Tax Return form, whether this is done on paper or electronically.
• Company Tax Return data is subsequently entered onto the COTAX system either manually or by electronic transmission, which is another point at which data may be altered due to human or software error.

There is a risk that errors involving very large profits or tax amounts may distort the overall statistics. To mitigate against this, checks are conducted on the analysis database before the statistics are produced, and any incorrect large values detected are altered.

In addition, companies are classified by industrial sector using the SIC 2007 standard and the Summary Trade Classification (STC) codes. The quality of the statistics is limited by the accuracy and consistency with which these codes have been assigned. To deal with known issues, some adjustments and corrections are made before the statistics are produced.

Nonresponse error

When analysing tax liabilities for the latest available year, figures are not necessarily available for all companies, as a small number may not have completed their Company Tax Return by the required date. The figures presented show the liability for the latest year based on those that have submitted their returns by the deadline. Statistics that include very late returns will be available in the following year’s publication, by which time almost all companies will have completed returns and assessments, and this error will have been mitigated.

Processing error

It is possible that errors exist in the programming code used to analyse the data and produce the statistics. This risk is reduced through developing a good understanding of the complexities of CT, and thoroughly reviewing and testing the programs that are used.

6.4 Data revision

Data revision - policy

The United Kingdom Statistics Authority (UKSA) Code of Practice for Official Statistics requires all producers of Official Statistics to publish transparent guidance on the policy for revisions.

Data revision - practice

This analysis is published annually and includes an estimate of liabilities for the latest financial year, along with revisions for the previous four years. The revisions for previous years are normally small but reflect the latest position for companies and any new data received since the previous publication.

Company CT assessments are subject to revision and although the majority of assessments are finalised within two years, there are exceptional cases that can take much longer. There is, therefore, no specific point at which all the CT liabilities for a particular year can be considered as ‘final’.

The statistics in this analysis are revised each year for the five years prior to the latest published year. Reasons for changes in liabilities include:

• revisions to the assessment, for example to carry back losses from later years, or because of an HMRC enquiry
• amendments to correct errors in the original assessment
• late submission of the company’s tax return, replacing the imputed figures in the previous release of the statistics

Receipts statistics may be revised following the end of the financial year when an annual reconciliation of receipts recorded for each tax/duty takes place ahead of publication in the HMRC Trust Statement. From this point the total receipts figure is final, but the split between trade sectors may change for the over the next few years, as the allocation of payments within company groups is finalised. This could lead to a discrepancy between this and other HMRC publications.

6.5 Seasonal adjustment

Seasonal adjustment is not applicable for this analysis.

7. Timeliness and punctuality

7.1 Timeliness

There is a difference in the timeliness of Corporation Tax receipts and liabilities data. This is due to when companies must pay their CT (receipts) compared to when they submit their CT Return form (liabilities), and also how we aggregate the data for analysis.

Data for both receipts and liabilities are aggregated into financial years, which run from 1st April until 31st March the following calendar year.

Company Tax Returns can be submitted up to 12 months after the end of a company’s accounting period. However, small companies must make their CT payment within 9 months after the end of their accounting period. Large companies pay CT using a system of Quarterly Instalment Payments (QIPs). This causes a time lag between receipts and liabilities that differs depending on the size of the company.

Therefore, companies typically pay their CT (receipts) before they submit their CT return (liabilities) for that financial year. Receipts information is available for analysis the day after they are received by HMRC and so analysis on receipts can be provided for the latest complete financial year.

However, companies have up to a year to provide HMRC with returns stating their CT liability so the most recent liability information available is for the year preceding the latest complete financial year - in other words, one year behind receipts.

This analysis is published in the autumn, providing statistics for financial years that end in March. The reason for the delay is due in part to the time required to complete the complex analysis and quality assurance. It is also due to Company Tax Returns being submitted late – passed the 31st March deadline. If publication was brought forward to earlier in the year, there would be many missing returns for which imputed data would be necessary. This would lead to less reliable statistics being released.

7.2 Punctuality

In accordance with the Code of Practice for official statistics, the exact date of publication will be given not less than one calendar month before publication on both the Schedule of updates for HMRC’s statistics and the Research and statistics calendar of GOV.UK.

Any delays to the publication date will be announced on the HMRC National Statistics website.

The full publication calendar can be found on both the Schedule of updates for HMRC’s statistics and the Research and statistics calendar of GOV.UK.

8. Coherence and comparability

8.1 Geographical comparability

This analysis is presented for a single region - the United Kingdom.

8.2 Comparability over time

For all years included in the publication data from 100% of companies is used and this allows for easy comparison over time.

8.3 Coherence - cross domain

The only instances of different sources being used to provide data for the same variable is for a company’s SIC 2007 code and their estimated SME status.

Companies do not report their SIC 2007 sector to HMRC as part of their CT return or registration, so they have been assigned to a sector based on data from external sources; this is predominantly matching records to Companies House Free Data Product and the Office for National Statistics’ (ONS) Inter-Departmental Business Register (IDBR) survey.

Quality assurance checks are undertaken on SIC code analysis, but since the codes are standardised, coherence issues should be minimal and not impactful.

Industrial sector is categorised in two ways - UK Standard Industrial Classification (SIC) 2007 and Summary Trade Classification (STC) codes. These standards are significantly different this could lead to coherence issues when comparing some of the data.

To mitigate the risk of confusion, the categorisation used in each piece of analysis is clearly stated. In addition, work is underway to migrate all industrial sector categorisation to SIC 2007.

The CT liabilities analysis additionally includes a breakdown by estimated small and medium-sized enterprise (SME) status. The criteria used to determine a company’s SME status are employees, assets and turnover.

Not all of the information is collected by HMRC as part of CT returns and registrations, and so external data is also used from the IDBR and information provided by companies to Companies House and accessed through Bureau Van Dijk’s Financial Analysis Made Easy (FAME) product.

Comparable variables between data sources are chosen to minimise the risk and impact of coherence issues.

8.4 Coherence - sub-annual and annual statistics

All statistics are presented as annual outputs. No coherence issues exist.

8.5 Coherence - national accounts

This publication shows CT receipts and liabilities for each financial year. For National Accounts purposes the receipts figures are time shifted to produce values on a National Accounts Basis (NABs); this is based on due dates for payments which are different depending on the size of company.

8.6 Coherence - internal

Rounding of numbers may cause some minor internal coherence issues as the figures within a table may not sum to the total displayed. Effort has been made to ensure totals between tables remain constant where appropriate.

9. Accessibility and clarity

9.1 News release

There haven’t been any press releases linked to this data over the past year.

9.2 Publication

The tables and associated commentary are published on the Analyses of Corporation Tax receipts and liabilities webpage of GOV.UK.

Tables are published in the OpenDocument format, and the associated commentary as an accessible PDF.

Both documents comply with the accessibility regulations set out in the Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018.

Further information can be found in HMRC’s accessible documents policy.

To improve accessibility further, the possibility of moving the commentary from PDF into an HTML format is being investigated.

9.3 Online databases

This analysis is not used in any online databases.

9.4 Micro-data access

Access to this data is not possible in micro-data form, due to HMRC’s responsibilities around maintaining confidentiality of taxpayer information.

9.5 Other

There aren’t any other dissemination formats available for this analysis.

9.6 Documentation on methodology

Background and guidance to interpreting Corporation Tax statistics is publicly available to users.

9.7 Quality documentation

All official statistics produced by KAI, must meet the standards in the Code of Practice for Statistics produced by the UK Statistics Authority and all analysts adhere to best practice as set out in the ‘Quality’ pillar.

Information about quality procedures for this analysis can be found in section 4 of this document.

10. Cost and burden

Because all necessary data for the Corporation Tax National Statistics is obtained from an administrative data source, COTAX, there is no additional burden on companies or HMRC tax inspectors to provide information.

It is estimated to take about 30 days FTE to produce the annual analysis and publication.

11. Confidentiality

11.1 Confidentiality - policy

HMRC has a legal duty to maintain the confidentiality of taxpayer information.

Section 18(1) of the Commissioners for Revenue and Customs Act 2005 (CRCA) sets out our duty of confidentiality.

This analysis complies with this requirement.

11.2 Confidentiality - data treatment

The statistics in these tables are presented at an aggregate level so identification of individual companies is minimised, but potentially still possible. Aggregate data categorised by SIC 2007 code, has the potential to be disclosive.

Where potential risks exist, statistical disclosure control (SDC) is applied to cells within tables. SDC is the application of methods to ensure confidential data is not disclosed to parties who don’t have authority to access it.

SDC modifies data so that the risk of data subjects being identified is within acceptable limits while making the data as useful as possible.

Disclosure in this analysis is avoided by applying rules that prevent categories of data containing:

• small numbers of contributors, and
• small numbers of contributors that are very dominant

If a cell within a table is determined to be disclosive, its contents are suppressed either by removing the data or combining categories.

Further information on anonymisation and data confidentiality best practice can be found on the Government Analysis Function website.