HM Revenue and Customs (HMRC) has released the latest edition of its technical guidance for tax professionals, outlining a series of mandatory security shifts and significant changes to how Making Tax Digital (MTD) is being enforced. Issue 147 of the Agent Update, published on 17 September 2026, serves as a final warning for firms to update their security protocols before a major deadline later this month.
The most immediate change for tax agents is the final phase of mandatory multi-factor authentication (MFA) for agent accounts. HMRC has confirmed that this phase will begin on 28 September 2026. Between this date and 15 October 2026, any agent accounts that have not enabled MFA will be subject to the new security requirements, potentially resulting in account lockouts for those who are unprepared.
Professional bodies, including the ICAEW, have urged firms to ensure all staff accounts have MFA active before the 28 September deadline to avoid service disruption.
Enforcement of Making Tax Digital (MTD)
HMRC has also confirmed that it has begun the process of automatically registering taxpayers for MTD for Income Tax. This move targets individuals who were mandated to join the scheme in April 2026 but who failed to sign up manually.
Taxpayers who are automatically registered must still ensure they use MTD-compatible software to maintain their records and send quarterly updates.
Looking ahead, HMRC reiterated the phased rollout for lower income thresholds:
- April 2027: Mandate extends to those with income over £30,000.
- April 2028: Mandate extends to those with income over £20,000.
Agents have been advised to review clients who may have been automatically registered since the initial mandate began.
Updates to Forms and Technical Guidance
The update includes several procedural changes regarding tax forms and specific duty rates. HMRC has confirmed a dual-acceptance period for form P87, used for claiming income tax relief on employment expenses. Both the old and new versions of the form will be accepted until 1 November 2026, after which the old version will be officially withdrawn.
Technical guidance has also been refreshed in the following areas:
Cryptoassets and Estates: New guidance has been issued regarding the tax treatment of cryptoassets held within deceased estates. This addresses the complexities of valuation and the timing of disposals during the administration period.
General Betting Duty: Clarifications have been added to the General Betting Duty guidance to ensure the correct application of recent rate changes. This is particularly relevant for agents representing bookmakers and betting exchanges.
Agents are encouraged to review the full technical clarifications added on 18 September 2026 to ensure their clients remain compliant with the latest reporting standards.