HMRC + Companies House Joint Filing Service Closes 31 March 2026

One of the most practical “back-office” changes for UK companies is now fixed in the calendar: the online service that allowed businesses to file Company Tax Return (CT600) and accounts together is set to close on 31 March 2026.

For many small companies, this portal was the simplest low-cost route. Its closure changes how businesses plan submissions, choose software, and manage compliance evidence.

What is closing and when

HMRC guidance states:

  • The online filing service will close on 31 March 2026.

  • You can still use it to file and amend your Company Tax Return with HMRC and file accounts with Companies House up to and including 31 March 2026.

  • From 1 April 2026, you will need to use commercial software to file annual accounts and Company Tax returns with HMRC.

The shift is not simply “new website.” It is a structural move away from free, manual filing toward software-based compliance.

What changes from 1 April 2026: practical impact

From April 2026 onward, many companies will need to:

  • Select commercial software that can produce and file required elements (CT600, computations, accounts).

  • Establish internal processes to keep accounting records in a format that can be exported reliably.

  • Manage access, approvals, and audit trail (especially if multiple directors approve filings).

For owner-managed companies, the most common pain point is timing: compliance becomes dependent on software setup and data hygiene, not just “end-of-year paperwork.”

Companies House is also moving to software-only accounts filing (from 1 April 2027)

A second change is already confirmed and should be planned together with the 2026 closure.

From 1 April 2027:

  • All companies must file their accounts using commercial software.

  • Companies House will close web and paper-based services for accounts filings (web services remain for other statutory filings).

  • The change applies whether you file yourself or through a professional.

In other words, even if you find a workaround in 2026, the long-term direction is software-only.

New disclosure expectations for small and micro entities from 1 April 2027

Companies House reforms also streamline filing options for small/micro entities:

  • Micro-entities will be required to file a copy of their balance sheet and profit and loss account.

  • Small companies will be required to file a copy of balance sheet, directors’ report, auditor’s report (unless exempt) and profit and loss account.

  • Companies will no longer be able to prepare and file abridged accounts.

For businesses that relied on reduced disclosure, this is a governance and commercial sensitivity issue (competitor visibility, client negotiations, credit terms). It also raises the bar for accounting quality: inconsistent categorisation and weak narratives become more visible.

What companies should do before 31 March 2026

A clean transition is very manageable if you treat it like a controlled migration.

1) Confirm your current filing method

  • Are you using the joint filing portal for CT600 and accounts?

  • What outputs do you produce today (accounts format, iXBRL conversion reliance, computations)?

2) Decide your “software strategy”

  • Minimalist strategy: basic compliance software + disciplined bookkeeping.

  • Managed strategy: accountant-led filing with structured monthly close routines.

3) Standardise evidence and audit trail
Software makes inconsistencies more obvious:

  • Director loan account discipline.

  • Expense categorisation rules.

  • VAT logic alignment (if relevant).

  • Payroll/PAYE reconciliation if the company has employees.

4) Plan a parallel run
Before the first live submission:

  • Produce a test export of accounts and computations.

  • Validate that CT600 logic matches your tax position.

  • Ensure director approvals and sign-off steps are clear.

How Yudey Law Firm UK can support

Yudey can turn these changes into a predictable process:

  • Corporate compliance mapping (Companies House + HMRC obligations).

  • Annual accounts preparation and submission workflow design.

  • CT600 filing support through commercial software routes.

  • Bookkeeping recovery and clean-up, including prior period corrections where needed.

  • Ongoing outsourced finance function for SMEs who want stability rather than deadline stress.

If you act before March 2026, the transition is a controlled upgrade. If you delay, it becomes an urgent rebuild.