HMRC have published their Agent Update for May 2026. We have summarised the key content, including mandatory tax adviser registration, VAT return submission deadlines, claiming Personal Tax refunds, and support for taxpayers during the Iran crisis.

HMRC have published their Agent Update for May 2026. We have summarised the key content, including mandatory tax adviser registration, VAT return submission deadlines, claiming Personal Tax refunds, and support for taxpayers during the Iran crisis.

The Approved Mileage Allowance Payment (AMAP) rate has increased for the first time in 15 years. The rate applied to the first 10,000 business miles travelled by employees per year will increase from 45p to 55p and will be backdated to April 2026. The increased rate will also apply to the simplified expenses regime for the self-employed in 2026-27.

HMRC have published new advisory fuel rates for company car drivers that apply from 1 June 2026.

The government has launched a consultation to seek views on the design and delivery of the High Value Council Tax Surcharge (HVCTS), which is due to come into force from April 2028. Proposals reveal how HVCTS is likely to work in practice.

In March 2026, Torsten Bell MP, the Minister for Pensions, informed the House of Commons that NS&I had identified an issue where the estates of deceased customers were not always repaid money from all of their accounts following a bereavement claim. NS&I have now published a 'delivery plan' setting out how this will be rectified, and the tax implications for estates.

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HMRC’s mandatory registration of tax advisers has now begun. Agents who interact with HMRC about someone else’s tax affairs have three months from their ‘start date’ to register. The first start date of 18 May applies to advisers interacting with HMRC without an Agent Services Account, Self Assessment or Corporation Tax account, as well as new advisers.

In Beer Express Ltd v HMRC [2026] TC09873, the First Tier Tribunal (FTT) found that project expenditure did not qualify for Research & Development (R&D) relief in the absence of evidence from a competent professional. The FTT placed no reliance on vague and loosely termed reports prepared by an R&D advisory firm that could not be reached when the claims were challenged.

As proposed at Budget 2025, HMRC have introduced a targeted advance assurance service for Research and Development (R&D) tax relief claims. The service, which is a pilot, aims to provide Small and Medium-sized Enterprises (SMEs) with clarity on complex or high-risk areas before a claim is made.

The application process for mandatory tax adviser registration opened on 18 May 2026. In light of this, HMRC have issued a press release encouraging advisors to check whether they need to register.

In Mark Gadsden v HMRC [2026] TC09884, the First Tier Tribunal (FTT) found that a taxpayer had exercised due care and diligence. It allowed his appeal against HMRC's refusal to treat his late-paid Class 2 National Insurance contributions as paid for State Pension purposes.
