Thanks - I spoke with an agent on Friday (0300 200 3300), who checked my return and confirmed everything had been input correctly and the correct amount of tax paid. They could not understand why I had been sent the letter and were a bit perplexed about how unspecific it was. I tried calling the child benefit specific line (0300 200 3100) to query why I had been sent it and why it was so vague, but was on hold for over an hour and then cut off. All in all, an unfortunate waste of time, but I understand these issues happen.
I completed my tax return for 21-22 online in January and paid the tax owed at that point. I now have a letter saying I may need to amend the return for the HICBC. Looking back at the return, I input the CB payments I received correctly and my salary correctly - so wouldn't that have calculated what I owed via the HICBC at that point? I don't have anything different to input, as it all looks correct, so I'm a little confused as to what to do.
Thanks very much in advance.