The Institute of Chartered Accountants in England & Wales (ICAEW) has warned that HMRC has begun adjusting taxpayers’ self assessments. The accountancy body said that one of its members recently had a query from a client who was sent a tax bill in which HMRC made an adjustment to the SA return arising from an underpayment in the 2010/11 PAYE code relating to an earlier year.

The ICAEW member was concerned as neither he nor his client was told of the adjustment much less the reason, which reduced the chances of the error being detected. He did not feel it ”appropriate for HMRC to make such adjustments without telling...