Tagged “HMRC”

2 articles, newest first.

• Amending a CIS return: the spec says don't, the schema can't, and HMRC decides by letter

  24 September 2026 ·18 min read

  HMRC's software spec says CIS return corrections must not be sent online. Everyone sends them anyway, the schema can't say "replace", and a letter with a 14-day deadline decides the rest.

  CISconstruction industry schemeCIS300HMRC

• The BACS hash: HMRC's payment check that sounded good and caught nobody

  23 August 2026 ·13 min read

  For eleven years payroll software had to send HMRC a SHA-256 hash of every Bacs payment so they could check the money matched. It couldn't tell who was paid, and one email retired it mid-year.

  RTIFPSBACSSHA-256