One in five teachers say their school has asked parents for money to help with funding, a poll found.
It also indicates that many schools are renting out buildings and grounds or even accepting advertising in bids to raise cash.
The small-scale survey, which questioned 900 members of the National Education Union (NEU), comes amid continuing concerns about a squeeze on school budgets.
Ministers have insisted that more money is going into schools, although earlier this month the Education Secretary did acknowledge that funding is "tight".
Overall, one in five of those questioned (20% of both primary and secondary members) said that their school had asked parents for money to help with school funding in the current academic year.
Nearly half said that their school had asked mothers and fathers to pay for specific items to help with their child's education, such as materials for art or design and technology and text books.
Nearly two thirds (64%) of secondary school staff polled, and just over a third (35%) of those working in primaries said their school was renting out buildings, with 49% of secondary and 20% of primary NEU members saying schools were renting out grounds.
Some 5.5% of those in secondaries and 3.5% of those in primaries said their school had accepted advertising on its premises.
The poll was published as the NUT section of the NEU met for its annual conference in Brighton.