Adult coloring books with the word "adult" in the title or subject category code cannot be sold through Ingram's distribution channels in the UK and Europe, because "adult" coloring books are considered stationary. Her Majesty's Revenue and Customs in the United Kingdom has determined that UK sales tax (referred to as VAT) must now be charged on coloring books that are intended for adult use only. We are not set up to collect VAT tax for stationary and for this reason, we removed all adult coloring book titles from POD distribution in the UK and Europe.
Further information on the current HMRC VAT rules for printed books can be found at https://www.gov.uk/government/publications/vat-notice-70110-zero-rating-of-books-and-other-forms-of-printed-matter/vat-notice-70110-zero-rating-of-books-and-other-forms-of-printed-matter
These changes do not apply to sales tax rules in the US or those outside of the United Kingdom and the European Union.