Free to be He-She – By Janon Fisher and Leela de Kretser

City-Paid Gender Op – Talk about a tax cut.

A judge has ordered taxpayers to foot the bill – up to $20,000 – for a sex-change operation that will make a 21-year-old man into a woman.

In a ruling to be released Thursday, Manhattan Family Court Judge Sheldon Rand said the city must provide the subsidized snip because the woman wannabe, identified as Mariah Lopez, had been in the care of the Administration for Children’s Services as a youngster.

The judge said the agency has a duty to pay for all “necessary” medical care to the kids in its charge.

Rand ruled that Lopez suffers from a diagnosed gender-identity disorder and that surgery is the recognized treatment.

“I don’t think it’s hit me yet. The consequences are so far reaching,” a jubilant Lopez told The Post after learning of her victory in the legal battle, which started before Lopez was 18 and cared for by ACS.