HMRC said phonelines were down due to a ‘short-lived technical issue’ on 15 January between 11.40am and by 2.15 over the busy lunchtime period. This affected the crucial self assessment helplines with callers reporting they could not get through to speak to an adviser.

The outage came during the busiest period for taxpayers with the self assessment deadline for 2024-25 tax returns on Saturday 31 January.