The Treasury set initial and dynamic interest rates for unpaid (7.75% initially) and overpaid (2.75% initially) amounts of Multinational Top-Up Tax and Domestic Top-Up Tax, effective from April 17, 2026.

These Regulations, made by the Treasury under powers in the Finance Act 1989, amend the Taxes (Interest Rate) Regulations 1989 to establish the specific annual interest rates applicable to unpaid and overpaid amounts of Multinational Top-Up Tax and Domestic Top-Up Tax, commencing on 17th April 2026.

The 2025 regulations amended multiple existing tax regulations, increasing the interest rate payable to HMRC on outstanding tax liabilities.

The Taxes and Duties, etc (Interest Rate) (Amendment) Regulations 2025 amend several existing regulations to increase the interest rate on unpaid taxes owed to HMRC. The changes affect various tax areas, including income tax, air passenger duty, and customs duties, raising the interest rate by 1.5% in each affected area.

The regulations came into force on April 6, 2025, and are supported by prior legislation.

The regulations amended the Taxes (Interest Rate) Regulations 1989 to increase the official interest rate for employment-related loan tax calculations.

The Taxes (Interest Rate) (Amendment) Regulations 2025, effective April 6, 2025, raise the official interest rate used to calculate tax on employment-related loans from 2.25% to 3.75% per annum.

This amendment modifies the Taxes (Interest Rate) Regulations 1989, impacting the tax liability for individuals receiving employment-related loans with interest rates below the new official rate.

The change aims to update the tax calculation to reflect current economic conditions and ensure fairer taxation on these types of loans.