The Dukes County government is looking into the potential of changing a state finance law so it could have a more stable rainy day fund.

Over the past few months, county commissioners have talked about petitioning the state legislature to allow Dukes County to retain larger amounts of its earnings, making it easier to cover expensive projects and other unexpected costs.

Right now, county governments in Massachusetts are funded by town assessments and revenues from other services, such as the registry of deeds. But, at the end of the fiscal year, counties can only hold on to 10 per cent of the assessment revenue if there is a surplus. The rest goes to offset future town assessments costs.

This differs from town governments in Massachusetts. Municipalities can retain all of their earnings at the end of the fiscal year, often putting money into stabilization funds.

Dukes County manager Martina Thornton said that even in years when the county makes robust earnings through the registry of deeds, the current state law makes it hard for the county to plan for larger capital costs. This has prompted interest in seeking more than 10 per cent.

For example, the county had approximately $1.3 million in revenue last year, $540,000 of which came from town assessments. The county can only keep $54,000 if there is a surplus, Ms. Thornton said.

“Any time I have a bigger expenditure, I have to go and ask for funds,” she said. “We would like to keep more than 10 per cent of the assessment. It would give us more money going into the fiscal year for needed expenses or projects.”

That would require a change in state law. Ms. Thornton said the county is planning to talk to the towns about the issue to see if they are amenable before sending petitions to the state legislature.

“We’d like to prepare presentations to the towns and the general public to explain why we are proposing this,” she said. “This is important because it would basically lessen the credit to the towns.”

That push is expected later this year.

Christine Todd, the chair of the Dukes County Commissioners, was open to raising the limit to potentially 20 per cent or higher. That could help the county be a little more proactive in maintaining its assets and programs.

“We felt if we could increase the amount of money we could keep it might give us more security,” said Ms. Todd. “Even if they gave a little more, it would be helpful. I think 20 per cent is a good place to start.”

Getting towns on board is essential to moving the idea forward, other commissioners have said.

“There’s a difference between what you desire and what you deserve,” said commissioner Peter Wharton at an April meeting. “I think we’ve got to really prove to the people in this county that we deserve this and why.”

Commissioner James Klingensmith felt that only being able to hold onto 10 per cent, has been holding the county back.

“I believe the county of Dukes County is suffering for it,” he said. “We need to get this moving.”