Gov. Janet Mills is expected to sign into law a bill that advocates say could substantially increase the number of affordable housing units built in Maine over the next eight years.

The measure would provide the first state-level tax credits to developers building new homes and apartments for poor and elderly Mainers and preserve existing rural housing.

Up to $10 million a year would be allocated to leverage federal funds and private investment for new housing. Advocates say it could create 1,000 new units and save another 500.

“This proposal represents the largest investment that Maine has ever made in creating and preserving affordable homes, and it couldn’t come at a more critical time,” said Greg Payne, director of the Maine Affordable Housing Coalition, in a statement.