Mother-in-law, 64, currently works full time at a well-known retail company. She received a letter from debt collection agency stating she owes HMRC £6K in unpaid tax. She has said this is the first she has heard of this debt but we can only take her word on this. We called HMRC and they said the unpaid tax is from pension income (2018 to present day) not being taxed. Approx 10 years ago she was contacted by a pension company (presumably administrator of pensions for retail company she works for) regarding a defined benefit pension. Although she has not yet retired, she had to claim a lump sum + monthly income or risk losing it (I don't know much about this aspect). In any case, it turns out that this monthly income has never been taxed since. She has now set up a payment plan to repay £165/month and we need to follow up with her employer/pension provider to ensure future pension income is taxed on her payslip. ---------- Some questions if anyone can help: Shouldn't her employer/pension provider have taken tax on this income via her payslip from the start (since she's still employed by them)? If so, are they at fault for this? Question 2: If HMRC know that there have been years of unpaid tax, wouldn't this have been flagged earlier before such a large amount had been accrued? Many thanks! Lee