Correspondence

Edition 6: Making Tax Digital for Income Tax — software developer newsletter

Published 28 August 2026

Welcome to the August edition of the Making Tax Digital (MTD) for Income Tax software developer newsletter.

This edition includes:

• API lifecycles changes and actions for developers
• live service updates
• GOV.UK guidance updates
• HMRC’s planned MTD communications
• developer engagement, feedback and key dates

As the service continues to evolve, these updates are intended to help you plan ahead, support your users, and understand where HMRC is making improvements.

API lifecycle updates

Priority actions — APIs to review now

Some API versions are deprecated and are progressing towards retirement. Developers should review their current integrations and plan migration activity where needed.

API	Version	Retirement date	Required action
individuals-capital-gains-income-api	V2	16 October 2026	migrate to V3
individuals-reliefs-api	V2	16 October 2026	migrate to V3
individuals-losses-api	V6	1 August 2028	Customers filing their return for 2025 to 2026 through software should use V6. Customers filing their return for 2026 to 2027 through software should use V7.

Early migration is recommended to reduce the risk of integration issues or service disruption.

Actions for software developers

Developers should:

• review the API versions currently used in your software and check for dependencies on deprecated or retiring APIs
• migrate to the latest supported versions where available
• review the latest API versions, deprecation timelines and retirement dates on the Making Tax Digital for Income Tax roadmap

Delaying migration may increase the risk of:

• integration failures
• service disruption for users
• last minute remediation work

Live service updates

Confirmed live service issues (LSIs) and investigation updates continue to be shared through the weekly LSI log, distributed each Friday. Before reporting a new issue, review the latest LSI log and Making Tax Digital for Income Tax guidance.

If the issue remains unresolved, raise it through your Digital Relationship Manager, if you have one, or your MTD Account Manager by emailing makingtaxdigital-softwarevendors@hmrc.gov.uk. Ensure the LSI template is completed with all relevant information.

To support investigation, ensure you provide:

• a detailed description of the issue
• any error messages received
• relevant screenshots showing where the process is failing

‘Client/agent not authorised’ — what to do next

We continue to receive reports of ‘client/agent not authorised’ errors. Recent investigations have not identified these as LSIs.

Before raising an issue with HMRC, ensure the troubleshooting guidance previously shared through the weekly LSI log for ‘client/agent not authorised’ errors has been followed, as many cases can be resolved through these checks. Common causes include:

• incorrect sign in details
• authorisation issues
• MTD enrolment mismatches

If the issue still persists after these checks, the affected individual or agent should contact HMRC so that the specific circumstances of the case can be reviewed against their records and authorisations.

Customer support

Where further support is required, please refer customers to Use Making Tax Digital for Income Tax - Help and support.

The correct helpdesk contact number can be found on the Self Assessment: General Enquiries contact page.

Agents, should be directed to Agent Dedicated Line: Self Assessment or PAYE for individuals.

Service availability

The next planned downtime is from 5pm on Friday 11 September 2026 to 1pm on 15 September 2026.

Due to scheduled maintenance, you will be unable to access our online services during this period.

Plan accordingly and check the API Platform Status page regularly for service availability updates.

GOV.UK guidance updates

Recently published

Self Assessment Legal Framework (SALF) Manual

MTD for Income Tax content is now available within the SALF Manual, providing agents and other specialist users with additional technical guidance on the legislative framework supporting MTD for Income Tax.

HMRC Digital Assistant

A link to HMRC’s Digital Assistant has been added to the Help and Support section of the Use MTD for Income Tax guidance, giving customers another way to access HMRC support.

Sign up guidance

From September 2026, HMRC will begin signing up customers who should be using MTD for Income Tax for the 2026 to 2027 tax year but have not yet signed up. Customers affected will be contacted directly by HMRC.

Read more information at check what to do if HMRC has signed you up for Making Tax Digital for Income Tax.

Coming soon

Exemptions guidance

Additional guidance is being prepared to cover changes in customer circumstances, when exemptions become available, and when an exemption no longer applies.

Interactive guidance enhancements

Further improvements are planned to help users identify which exemptions apply to them and provide more tailored guidance within the tool.

Future guidance priorities

HMRC continues to work with stakeholders to shape future guidance products and identify areas where additional support may be beneficial.

HMRC’s planned MTD communications

This section highlights planned HMRC communications activity from September to December 2026, to help you understand the messages customers and agents are likely to receive over the coming months.

Communications will focus on supporting customers already using MTD for Income Tax and preparing the next cohort of sole traders and landlords earning £30,000 to £50,000 ahead of mandation from April 2027.

September

• launch of marketing campaign for the £30,000 to £50,000 cohort
• launch of HMRC social media activity for both the over £50,000 and £30,000 to £50,000 cohorts
• HMRC communication activity, including customer, agent and stakeholder communications

October

• ‘6 months to go’ communications for customers who will join MTD for Income Tax from April 2027 — news release and HMRC social media activity
• continued readiness messaging for customers, agents and stakeholders
• marketing campaign and communications supporting the upcoming quarterly update deadline

November

• continuation of marketing campaign and reminder communications activity ahead of the 7 November quarterly update deadline
• direct agent communications and HMRC social media activity to support successful quarterly updates

December

• ongoing stakeholder, agent and customer communications, including seasonal awareness activity and future readiness messaging

As a reminder, HMRC recently published a press notice providing an update on progress to date and the next phase of delivery for MTD for Income Tax.

Get involved, feedback and support

Developer engagement and key dates

Stay connected and keep up to date with the latest MTD for Income Tax developments through upcoming forums and events. Key upcoming dates:

• technical forum: 8 September 2026
• quarterly updates (Q2): 07 November 2026

Help shape future newsletters

We are always looking to improve our communications with software developers.

Please take a few minutes to complete our Software Developer Feedback Survey and let us know what content you would find most useful in future editions.

Developer queries

To help us manage and respond effectively, send all developer queries to makingtaxdigital-softwarevendors@hmrc.gov.uk.

Next edition

The next edition is planned for September 2026.

Thank you for your continued engagement and support. We look forward to sharing further updates in the September edition.