CIOT News states:
"Self-assessment and incorrect dates of birth
Having the correct date of birth on a client’s self-assessment return is very important. When the return is submitted, HMRC’s systems take the date of birth supplied and use it to update at least 16 other systems. This means that an incorrect date of birth can impact your client’s state pension, Personal Tax Account and even ability to use voice recognition on HMRC helplines.
HMRC tell us that there has been a large increase in the number of returns submitted by agents where the date of birth is wrong – sometimes significantly so. We have therefore been asked to remind members to check (or ask their clients to check) that dates of birth on self-assessment returns are correct."
Surely HMRC does not change something that should be permanent and checkable against other databases e.g. Birth and Death records without going back to the taxpayer first and querying the conflict in DOB? If it does then it should modify its systems!