Just come home to a nice letter from HM Revenue & Customs saying I owe them money..... £1,500. Reading the 6 pages of calculations and guidance notes it's because: Wrong Tax code 08-09. Wrong Tax code 09-10. It changed to claw back underpayment from 08-09, but they didn't claw back enough. Wrong Tax code 10-11. Again, was altered to claw back underpayments from 08-09 & 09-10 but they got it wrong leaving me owing £1.5k which they say they'll take using my tax code during 11-12. Anybody knowledgable on this? Been through a similar situation or have advice? I'm going to go back through my payslips/P60s and check on company car details for the period as this is where they keep cocking up. Not happy..