Does this happen to everyone? Every year of self-employment I get letters telling me that I owe money, whether I have already paid my SA or have set up a payment plan. This year I've had to phone up twice after receiving multiple letters, a good two hours each time. Both times I was initially told that I owed a certain amount, but then after I explained I was on a payment plan, being told that they could now see I was on a payment plan... and that the system hadn't been updated, which was why I received the letters threatening to send my case to a debt collection agency. Same thing happened last year. All sorted now and the person I spoke to was very helpful and sorted everything, but is this a good waste of peoples time and money, both at HMRC and sole traders?