Almost one in ten records within the Inland Revenue's frameworks database contain errors, the government has admitted.
The frameworks database feeds information into various other databases held not just by HMRC but other departments too.
The problems came to light after enquiries by Tory MP for Putney Justine Greening concerning a constituent who found errors on their records. Mistakes were found in 3.5m records from a total of 47m.
Greening told The Register: "It shows there are substantial problems with records so it is no wonder there are problems with tax returns and probably tax credits too. Many people are probably unaware what is wrong."
She said she had tried to investigate why her constituent had their record changed wrongly, but the Treasury was very vague about what the process was for changing records - the department would only say that they can be changed for "business needs".
Greening will be asking more questions on this issue when the House gets back to work.
The frameworks database only contains quite simple information - first, second and surname, title, sex, data of birth, address and National Insurance number. Which begs the question of how many errors more complicated government records contain. It costs £7.5m a year to maintain it.
Even more worrying of course is the government's continued enthusiasm for more and more databases, and the ID card scheme, which makes such errors ever more damaging and difficult to correct.
In other news Sir Michael Scholar, head of the UK Statistics Authority, said today government ministers should no longer have advance notice of controversial statistics in order to restore trust in such figures, according to the Times.
Scholar clashed with the government before Christmas when he criticised the Home Office for prematurely leaking figures on knife crime. ®