The property-tax exemption program that has played a central role for decades in the construction of apartment buildings across New York City appeared headed for trouble as negotiations bogged down between developers and construction unions.

Under the terms spelled out in a law passed last June by state legislators, and signed by Gov. Andrew Cuomo, the two sides are supposed to produce a memorandum of agreement by Friday on a construction-wage formula to save the tax exemption.

If they fail to agree, the tax program known as 421-a will automatically end.

Jerilyn Perine, the executive director of the Citizens Housing and Planning Council, a housing advocacy group, said an end to 421-a would “make affordable housing more expensive to build.”

Read more in the WSJ.