I've been away for a bit and come back to a number of increasingly stern HMRC letters about unpaid PAYE/NICs for this tax year. A good few hundred quid too.

I'm baffled, my accountant says all the RTI submissions are up to date and there shouldn't be any NI/PAYE taxes due, so wants me to get on the blower to HMRC to find out what's going on.

Anyone came across this before?