The Committee also slated unacceptably high compliance costs for business, the unexpectedly high transition costs for the expansion of Making Tax Digital for Income Tax and declining productivity in compliance teams. There is also an over-reliance on old fashioned letters with 14 million pieces of post handled by HMRC in a single year.

The outdated IT means that HMRC is facing lower levels of security, lower reliability and resilience, and higher costs of system changes, warned the Treasury Committee in its Cost of the Tax System report, which was released after many in-depth witness sessions over the last six months before the Committee.