Edition 4: Making Tax Digital for Income Tax — software developer newsletter
Published 30 June 2026
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Welcome to the June edition of the Making Tax Digital (MTD) for Income Tax — software developer newsletter.
This edition includes updates on:
- API lifecycle changes and actions for developers
- recent service releases and improvements
- live service issues and known behaviours
- GOV.UK guidance updates
- communications and engagement opportunities
As the service continues to operate, these updates are intended to help you plan ahead, support your users, and understand where HMRC is making improvements.
We welcome your feedback to help shape future editions of this newsletter.
API Lifecycle
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.
The priority APIs to review are:
| 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 |
Early migration is recommended to reduce the risk of integration issues or service disruption.
API lifecycle updates — what developers should do
Delaying migration may increase the risk of:
- integration failures
- service disruption for users
- last minute remediation work
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 MTD for Income Tax roadmap
Latest service release: what has changed
Service updates now live
The latest functionality for the MTD for Income Tax service was rolled out on 16 June 2026, and all systems are now operating as expected following deployment.
This release includes functionality in to the live environment for:
- reporting partnership income
- reporting carrying back losses
- calculation results of student loan Plan 5
- updating the accounting method in year (change from end of year only)
Sandbox updates include:
- reporting winter fuel payments
- an additional data item to report adjustments to profits for class 4 National Insurance contributions
- the ability for users to view their penalty position in their software
Service guide updates include:
-
enhanced HMRC Assist guidance to support tax calculations
- support for building to the winter fuel payments functionality
- additions to the:
- minimum functionality standards
- process for production access
- viewing penalties position
- capturing the period of account
Live service issues (LSIs) latest updates
This section highlights:
- the most common issues reported by software developers in June
- guidance to help you resolve these issues quickly
- an understanding of where HMRC is already taking action
These LSIs are current to the week ending 26 June 2026.
New issues
| Issue | Impact | What to check and actions | Status |
|---|---|---|---|
| Reporting type mismatch | Quarterly and tax return may error or fail to fulfil obligations | No action required for software at present; HMRC is investigating and correcting records | Under investigation |
| Obligations not updating after reporting type change | Obligations may not appear after switching reporting type (for example, standard to calendar) | Allow time for updates; HMRC is investigating timing inconsistencies | Under investigation |
| Payments not processing from 16 June | Payments not processed and therefore not visible in accounts or through APIs | Issue resolved; payments now processed | Closed |
| Missing obligations after final declaration | Customers may be unable to submit quarterly updates | Advise users to wait up to 1 week before contacting HMRC | Under investigation |
| Repayment delays | Delays to customer repayments | Do not submit additional 2025 to 2026 returns using software; reassure users repayments will be processed | Under investigation |
Other known behaviours
| Issue | Impact | What to check and actions | Status |
|---|---|---|---|
| Incorrect reporting type in HMRC systems | Users may appear as ‘standard’ instead of ‘calendar’, affecting submissions | Check reporting type before submission; check again after a week and report if still not corrected | Under investigation |
| SA200 customers unable to sign up | Sign-up blocked with error message | Direct users to convert to SA100 through customer support | Action required |
| State pension inaccuracies | Incorrect income values may affect tax calculations | Use amend or create endpoints; fix due December 2026 | Fix scheduled |
| Business Source Adjustable Summary (BSAS) — Residential Financial Cost (RFC) issue | Invalid expense appears in calculations | Prevent RFC updates; reassure users values will still be handled through quarterly updates | Fix in progress |
| Missing obligations for some customers | Customers cannot submit quarterly returns | Records have been corrected; monitor and report if issues persist | Under investigation |
| Obligations not marked complete | Completed submissions still show as open | Do not prompt re-submission; monitor before taking action | Fix being prioritised ahead of Q1 submissions; continue to monitor |
General reminders
| Area | Key point | Action |
|---|---|---|
| Onboarding | New 403 error (‘Client_Not_MTD_Enrolled’) returned where a National Insurance number is not enrolled in MTD | Ensure customer is signed up before API call |
| End of year submissions | Additional information is now required for some customers (for example, confirming whether they are a company director). If this is not provided, submission may fail at the finalisation stage. | Ensure the required information is captured and submitted using the relevant endpoints before completing the return |
| Annual Investment Allowance (AIA) | Cannot be claimed in-year under cash basis | Remove AIA from in-year submissions (may require deleting and resubmitting); claim at year end |
Planned downtime
The next scheduled planned downtime is from 5pm on Friday 10 July 2026 to 9am on Monday 13 July 2026.
Read the latest planned downtime on the API platform status page.
HMRC takes strong consideration of the impact to customers ahead of scheduling any downtime. To ensure our systems function at the standard required we need to allow for these upgrades to be made.
Raising live service issues
Please continue to raise live service issues through your account manager by emailing makingtaxdigital-softwarevendors@hmrc.gov.uk.
Please make sure the LSI template is completed with the relevant details of the issue.
GOV.UK guidance updates
Recent updates
GOV.UK guidance has been updated to support how users understand MTD and interacts with your software.
Recent changes include:
- Using MTD guide — the Use MTD for Income Tax - Submit your tax return has been revised
- Find out if you can get an exemption from MTD for Income Tax — customers claiming averaging relief (SA104) for 2024 to 2025 will not be automatically exempt from MTD
- Apply for an exemption from MTD for Income Tax — clearer information added on appeal rejections
What’s coming next
Further updates to guidance are in progress to support users and improve clarity.
2026 to 2027 planning
Work is underway, with wider engagement across government teams starting shortly.
MTD guide improvements
A second round of user research has been completed, focusing on:
- the guide summary
- sign-up signposting
- improved quarterly updates guidance
The next focus will be on change of circumstances and help and support content.
Self Assessment Legal Framework (SALF) manual
This manual which covered the legal basis for the assessment and collection of Income Tax is being updated to reflect MTD. These changes are currently undergoing external consultation.
Exemptions guidance
New guidance is being developed to cover:
- changes in circumstances, where an exempt customer no longer qualifies
- when mandated customers become eligible for exemption
Communications update
This section provides an update on recent communications activity related to MTD for Income Tax.
Campaign assets reminder
We recently shared our forward look of communications activity, from July to September.
With our quarterly update marketing campaign starting in July, we’d like to remind you of the Ready to use assets - HMRC campaign resources available on Frontify.
Get involved, feedback and support
Developer engagement
Ways to engage and provide feedback include:
- HMRC Developer Forum on the HMRC Developer Hub
- next monthly MTD Technical Delivery Forum — 7 July 2026
- Software Developer Feedback Survey — take a moment to complete the survey to help HMRC improve future newsletters
Developer queries
To help us manage and respond effectively, please send all developer queries to makingtaxdigital-softwarevendors@hmrc.gov.uk.
Next edition
The next edition is planned for July 2026.
Future editions will include further updates on service developments, event outcomes and developer engagement activity.