Meals on Wheels volunteers are worried people may miss out if the county council streamlines the service.
The authority, which currently provides grants to providers in the county, is set to embark on a review to determine if efficiencies could be made.
Marlow House in Desborough, which receives a £9,000-a-year council grant, fears any savings made could leave some people without a hot meal.
Manager Julie Johnson said changing the system of assessment might mean a lot of people would no longer qualify, but she pledged her charity would continue deliveries.
She said: “We have served some of these people for years.
“We have got some people approaching 100. They are frail and aren’t able to cook.
“Losing that £9,000 is a big chunk for a charity like us but we are determined not to stop a service we have been providing for years.”
A county council spokesman said the authority was aiming to save £128m in all areas over five years.
On Meals on Wheels, he said: “No firm proposals are in place at the moment but there is the potential that we would look to introduce a county-wide service.
“Currently it is limited to just a few areas.
“A consultation will take place once clear proposals have been drawn up.”