Six Long Island communities have failed to fully comply with state affordable housing mandates, a newly released state audit says.

The municipalities — Hempstead and Mineola villages, and North Hempstead, Brookhaven, Islip and Babylon towns — fell short of the requirements of the Long Island Workforce Housing Act, which compels builders to include affordable housing in many new developments in exchange for permission to build more units, state Comptroller Thomas P. DiNapoli found.

In interviews and in written responses included in the comptroller’s report, local officials said they strive to abide by the law, but they said its requirements can be unclear.

The eight audited communities “generally complied” with the mandates, with some exceptions, DiNapoli wrote in the audit report released Friday.

The 2008 state law requires builders to designate 10 percent of new homes as affordable housing, for sale and rent, in exchange for a “density bonus” allowing more units. The law applies only to developments of five or more units on Long Island, and the affordable units are set aside for people earning up to about $105,000.

The comptroller reviewed eight municipalities’ building approvals from 2009 through 2014. During that time, local officials greenlighted 29 developments; 24 complied with the law, providing 1,000 affordable housing units, out of a total of 3,439 units.

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However, the villages of Hempstead and Mineola and the town of North Hempstead each approved a development without requiring the builder to include affordable housing or pay a required fee, the audit found.

In Hempstead Village, 30 percent of the 448 approved housing units were affordable, the report found. The village attorney, Debra Di Salvo, said officials did not mandate affordable housing in one 12-unit development that has not yet been built. It might be possible to require the builder to designate one unit as affordable housing, she said.

In Mineola, an unnamed official was quoted in the report saying it would be helpful if the state would provide guidelines for implementing and complying with the law.

In North Hempstead, spokeswoman Carole Trottere said officials “have revised our procedures to ensure that we are in compliance with this important law.”

The audit also found that the town of Brookhaven failed to establish guidelines governing its affordable housing trust fund. Under the law, developers can pay fees that go into trust funds to create affordable housing, instead of building affordable units. Brookhaven is now in “full compliance,” and it has never had any money in the fund since it has always required developers to build affordable housing instead of paying fees, said Diana Weir, the town’s commissioner of housing and human services.

In Islip, local officials did not make sure a developer set aside affordable units for qualified residents, the audit found. In a written response in the report, an unnamed Islip official said the town is making changes to comply with the law.

In addition, although Babylon Town required a developer to pay an affordable housing fee, it charged $240,000, instead of the $1.3 million required under the law, according to the audit. In a statement, Babylon Planning Commissioner Ann Marie Jones called the law’s use of the same formula to calculate fees for rental and for-sale housing units “impracticable and unreasonable.” In Babylon, 66 percent of the approved housing units were affordable, according to the report.

Two of the audited municipalities — Huntington Town and Farmingdale Village — generally complied with the law, DiNapoli found.

Mitchell Pally, chief executive of the Long Island Builders Institute, a trade group, said the law leaves room for improvement: “Now is a very good time to look at the statute to make it better.”