Subscribers to electronic academic journals are facing hefty price increases this autumn as publishers add VAT to their rates.
Fred Friend, director of scholarly communication at University College London, said: "Libraries want to move to electronic versions as soon as possible to increase access to journals, but the tax is making it difficult."
Although printed books, magazines and journals are zero rated for VAT, Customs and Excise classifies electronic journals as a service, making them liable to a 17.5 per cent VAT rating.
Sally Morris from the Association of Learned and Professional Society Publishers said it was not in the interests of publishers to charge VAT because it required extra administration on their part and meant that libraries could afford fewer journals. In the past, publishers have often included electronic versions "free" with print subscriptions.
But this academic year, Cambridge University Press began to offer an electronic-only subscription package and cancelled its print-only subscription.
Lesley Boyle, business development manager at CUP, said that, as a result, the company could no longer avoid charging VAT.
"The library market is moving to electronic-only subscriptions," she explained. "There has been a rapid shift over the past year, so our selling models have had to change."
A spokesman for the Publishers Association said: "A book is a book. Whether it is a paper version delivered by a truck or an online version delivered by electronic means - there is a need to be consistent in the definition of a book."
Libraries are pushing publishers to reduce the charge for the electronic content to 80 per cent of the print price to compensate for VAT charges.