Corporation tax rates will remain unchanged following the Autumn Budget 2026, with the main rate held at 25% and the small profits rate at 19%.

The Government has also announced a range of measures and consultations to simplify corporation tax and encourage business investment. Some changes have confirmed start dates, while others remain proposals.

Let’s take a look at the main announcements…

R&D tax relief changes

The requirement to notify HMRC in advance of certain R&D tax relief claims will be removed for claims submitted on or after 1 April 2027.

A further consultation will look at simplifying both the technical rules and administration of R&D tax relief.

Company tax returns and computations

From 1 April 2028, amendments to company tax returns will need to be filed online, with only limited exceptions.

Plans to introduce prescribed tax computations will also go ahead, but on a longer timetable. A consultation on the full requirements will begin in early 2027.

Other announcements include:

– Reducing the threshold for the Advance Tax Certainty Service from £1 billion to £300 million.

– Providing greater clarity on the treatment of pre-development costs for capital allowances.

– Making Patent Box rules easier to apply.

– Exploring how to reduce complexity in the taxation of intangible assets, including differences arising from accounting standards, their treatment in partnerships and the taxation of intellectual property licences.

No changes to land remediation tax relief were announced, and the Government has not yet published its response to the earlier consultation on reforming the relief.

International tax and larger businesses

The Government has also outlined measures aimed mainly at larger companies and businesses with international activities. These include:

– Scrapping a separate reporting requirement for companies moving large sums of capital abroad.

– Considering simpler rules for overseas subsidiaries and arrangements treated differently for tax purposes in different countries, for the largest multinationals within the global minimum tax regime.

– Exploring simpler procedures for claiming treaty relief on interest, including an HMRC passport, limited self-assessment and better real-time information for lenders and borrowers.

– Reducing the scope of the new transfer pricing reporting schedule.

– Reviewing its approach to persistently non-compliant larger businesses.

End of the Advance Corporation Tax regime

The remaining Advance Corporation Tax (ACT) regime will be repealed from 1 April 2031. Any unrelieved surplus ACT balances still remaining at that point will be extinguished.

Companies holding these historic balances will therefore need to consider the implications before the regime ends.

What does this mean for you?

Although corporation tax rates are unchanged, the announcements could affect your company’s claims, reporting processes and longer-term tax planning. Many of the wider reforms remain subject to consultation, so their final scope and timing are not yet settled.

We’d strongly recommend keeping up to date on the results of these consultations to ensure you can plan for any changes in plenty of time.