Further amendments to Multinational Top-up Tax and Domestic Top-up Tax
Pillar 2 and the respective top-up taxes have been a feature of recent budgets with the OECD's framework being brought into force by the enactment of the Finance (No.2) Act 2023 (with subsequent amendments in Finance Act 2024 and Finance Act 2025).
In Autumn Budget 2025, the Government confirmed that further amendments would be implemented to ensure the UK legislation remains consistent with the OECD's GloBE rules commentary and administrative guidance. The amendments are not expected to raise any additional revenue and are described as measures to ensure the legislation works as originally intended.
Controlled foreign companies: interest on the reversal of state aid recovery
Following a Commission Decision ((EU) 2019/1352) the UK tax code was amended to recover amounts of State Aid from controlled foreign companies. This decision was overturned by a decision of the European Court of Justice on 19 September 2024, and the Government introduced regulations to allow companies to recover the tax which had historically been paid.
Under the existing law, interest was repayable on the amount of tax which was to be repaid but this did not extend to interest which the company had paid. The measure announced at the budget will extend that to allow for interest to be recovered on amounts of interest which were paid by companies.
Introduction of Carbon Border Adjustment Mechanism ("CBAM")
This is a new measure which places a carbon price on specified goods imported to the UK from sectors that are at risk of carbon leakage.
The UK CBAM will take effect from 1 January 2027 and looks to ensure that the UK reduces its global carbon emissions rather than moving carbon emissions overseas. The targeted areas are aluminium, cement, fertiliser, hydrogen, iron, and steel sectors. The measure is expecting to raise £250m a year by the end of the budget forecast.
For our analysis of the Sustainability related announcements, please read our Briefing: Autumn Budget 2025: a Sustainability Stocktake.
Transfer Pricing: SME Exemption and the International controlled transactions schedule (ICTS)
As part of its intention to reform the UK transfer pricing regime, the Government has confirmed its plans to introduce new powers for HMRC to be able to introduce regulations to compel in scope multinational companies to file an ICTS with HMRC.
This would be an annual filing requirement which would allow HMRC to collect information about relevant cross-border party transactions.
HMRC published both the policy proposal and the responses received to its initial consultation which was launched 28 April 2025.
- SME Exemption: The Government has been consulting about whether there should be reforms to the SME exemption from UK transfer pricing rules, particularly in relation to the exemption for medium-sized enterprises.
The Budget 2025 announcement, and release of the responses, show that this proposal has been dropped, with the reasons given relating to the potential compliance burden.
Note that the Government will continue to review whether they consider that the exemption should apply to medium-sized enterprises.
- ICTS: Transfer pricing is so often at the centre of compliance checks and enquiries opened by HMRC. HMRC is now being given powers to compel multinational groups to provide HMRC with the information which they will need either throughout an enquiry or to be able to assess on which groups of companies they should carry out a manual risk assessment.
The Government committed to this reform in its Corporate Tax Roadmap 2024, and the final proposal comes off the back of responses to the consultation carried out in the spring of this year.
These rules build on the updates made in 2023 to the UK transfer pricing regime, which required businesses to maintain their own transfer pricing records and provide them to HMRC upon request. The intention is to now have businesses file some of this data in a standardised format, the ICTS.
Nonetheless, the Government have confirmed that, to minimise costs, they would expect the filing requirements to be broadly aligned with similar overseas requirements. The initial consultation noted that thirteen of the nineteen other G20 members have a similar filing requirement. There is hope, then, that this additional requirement does not impose too dramatic an additional compliance burden on the approximately 75,000 companies that might be in scope for these new rules.
The primary legislation will be included in the Finance Bill 2025-26. HMRC will then issue regulations that set out the detailed design of the ICTS.
It is expected that the regulations will include details of the type of transactions that are to be included, from when companies will be required to file the ICTS, and the form and way such information is to be provided. A de minimis of £1m of aggregated foreign transactions is expected to apply. The Government has also indicated that transactions below a certain value threshold (currently proposed to be £100,000) would not need to be disclosed, although there will be specific rules aggregating similar types of transactions (for example those made with the same counterparty).
Given that there will be a further technical consultation in the spring of 2026, the Government expects that the measure will take effect for accounting periods beginning on or after 1 January 2027.