For years we've been putting A_GEN_TAX on any book with a CD/DVD/etc and paying full VAT to HMRC. My guess is most other used booksellers aren't paying them anything and we're the exception paying more than we should as this would be a mixed supply.

However this tax code seems to be creating problems with exports as amazon doesn't seem to handle marketplace facilitor on them, so they are not IOSS.

So two questions:

1) What amazon tax code (such as A_BOOKS_GEN) would a book with a CD/DVD included me?

2) Should we really be paying HMRC the full 20% VAT. My understanding is no, but that we don't have the information on the percentage of tax agreed by the manufacturer with HMRC for a mixed supply. So what rate of VAT should be being sent to them?