Authors have expressed outrage over expectations from schools that they should give talks or writing workshops for free, saying that offering their services for little or no money is "one of the worst things you can do".
Reduced budgets and an unwillingness among schools to prioritise creative arts mean that many writers are being asked to provide professional services for nothing, authors say.
School librarians have confirmed that they do not always offer payment to authors who come to speak to pupils.
The Society of Authors is also concerned about the development. Deputy chief executive Kate Pool said that tight council budgets had adversely affected schools and libraries.
"The effect is that authors are expected to do it for love, not money, in a way you'd never expect with a supply teacher," she told TES. "There's a perception that everyone else should be paid but an author should do it for love. But they need to live as well. And a sought-after author is worth every ha'penny, in terms of the benefit children get in supporting reading and writing."
The concerns have been raised during Children's Book Week, which runs until Sunday.
Alan Gibbons, a former teacher and author of bestselling teen novel Shadow of the Minotaur, delivers regular writing workshops in schools. "It's clear that school budgets are being squeezed," he said. "Librarians are being made redundant. I've met librarians with zero budget or a pound;400 budget. They can barely cover books and periodicals.
"And I've come across school management teams that really don't see the point of the whole aesthetic. All that matters is Ofsted and tests. Reading for immersion and pleasure seems to be downgraded."
Mr Gibbons often spends more than five hours in school during a visit. He was recently asked to present a session on the 1258 Siege of Baghdad, which required considerable research. "It's not just 10 minutes' book promotion," he said. "Writers should be paid professional rates for professional work."
The Society of Authors recommends that writers should base their fee on the annual salary they would expect to earn. It suggests that children's authors and illustrators charge between pound;350 and pound;1,000 for a full-day visit, and between pound;150 and pound;800 for half a day, plus travel and expenses.
Antony Lishak, also a former teacher and an author of children's books, visits about 100 schools every year. "When most of us go in, it's a big performance," he said. "It would be an insult not to say there's a fee."
His visits are largely arranged through existing contacts. But, he added, when librarians or teachers search online for authors to deliver school visits, they will opt for whoever is cheapest.
This was echoed by author and illustrator Clara Vulliamy. Speaking to The Bookseller magazine, she said: "One of the worst things you can do is offer yourself at a lower price. That muddies the water and makes it harder for the rest of us."
Mlanie McGilloway, librarian at Churchill Academy in North Somerset, pays between pound;300 and pound;500 for author visits. "You wouldn't tell your plumber, `I have a leak. Will you come and sort it out? But I can't pay you,' " she told TES. "It's a very odd thing that people ask authors to do that.
"But it's desperate times. For a lot of schools, it's trying that out or getting no one at all."
Other librarians gave similar feedback to The Bookseller.