Speaking from experience, this kind of thing might - just - also be a clerical error. Not so long ago, a place I used to work for got one of these notices becau

Speaking from experience, this kind of thing might - just - also be a clerical error. Not so long ago, a place I used to work for got one of these notices because the Tax Department didn't agree with how we had calculated tax. Accounts did manage to sort it out, in the end.