If a company makes a mistake with its numbers then its accountants or other financial advisors should pick it up and, depending the severity, the company and/or directors may be punished.
So who checks on the Governments tax collecting section, HMRC. Well it’s the the National Audit Office (NAO) and they have just checked HMRC numbers and found they have been somewhat less than accurate – ooops!
http://www.accountingweb.co.uk/article/hmrc-apologies-after-getting-sums-wrong/560838