New HMRC service for agents to re-activate client Self-Assessment accounts

Following dialogue with the ATT and other professional bodies, HMRC are introducing a new service for agents to allow them to re-activate Self-Assessment accounts for their clients. 

The need to re-activate a Self-Assessment account normally arises if a taxpayer has previously filed tax returns, but either did not need to file a return for the previous year, or has been removed from Self-Assessment by HMRC but still wishes or needs to file a return. 

Re-activating an existing Self-Assessment record is recommended practice as it helps to avoid processing delays which can occur where a tax return is filed 'voluntarily' - ie without a notice to file a tax return having been issued by HMRC. 

From 1 October 2025, agents who need to re-activate a client’s Self-Assessment account can do so by calling the HMRC Agent Dedicated Line (ADL). This new service can only be accessed by selecting the relevant option from the ADL menu, as it will not be possible to be transferred from other HMRC helplines or to request this via web chat. HMRC have confirmed that it will be possible to discuss up to five clients per call.

There is no obligation to use the new service, as it will still be possible to re-activate a client's Self- Assessment account by completing an online SA1 (or Form CWF1 for the self-employed). However, the new service should enable agents to re-activate the Self-Assessment account more quickly than other methods.

The new service is available for Self-Assessment re-activations only. If the client was not previously in Self-Assessment, it will be necessary to follow the normal Self-Assessment registration process.