The Office for Civil Society is considering whether to continue to fund a huge survey of more than 100,000 charities that asks them about their relationships with local authorities.
The National Survey of Charities and Social Enterprises has cost £1.5m since it began in 2008.
It is believed to be the biggest survey of English charities ever conducted and involved two waves of research by Ipsos Mori in 2008 and 2010.
The results of the second wave, which revealed a sharp increase in the number of charities providing public services, were published last week.
A Cabinet Office spokesman said: "The national survey was contracted for two rounds, which have been completed.
"It was introduced as part of the system for measuring local authority performance, which has been removed. We will evaluate the benefits of the data to civil society organisations before making decisions about future research."
Roberta Blackman-Woods, the shadow civil society minister, said it was important the survey continued.
"We are seeing a withdrawal of information-gathering across a range of sectors," she said. "Because we might be relying more on civil society organisations to provide services, we especially need this data."
When the survey began in 2008, Phil Hope, the Labour third sector minister at the time, said it was "absolutely crucial to ensuring charities, voluntary groups and social enterprises get the support they need to help them thrive".
A total of 48,939 voluntary organisations responded in 2008, compared with 44,109 last year.
The results are broken down into local authority regions, as well as nationally.