It seems even the homeless can't escape paying rent in New York.

The city has started charging some families to stay in homeless shelters. The new policy only applies to residents who have an income from jobs.

It is based on a 1997 state law that was not enforced until last week.

Officials say the new rules stem from a 2007 state audit that forced the city to pay back nearly $2.5 million in state housing aid, and that only those who can afford the expense will be charged.

"It's a state law. My understanding is virtually every other county has been doing this for many years. We never did, we were audited by the state and they've made the decision," said Mayor Michael Bloomberg on Saturday. "We have to do it and we'll do it, whether it's good policy or bad policy."

About 2,000 families are expected to be affected by the new rule, and residents could pay as much as half their earnings.

The city's commissioner of Homeless Services said he did not see the policy playing out in an adverse way and said the goal is to move families back into their own homes.

Coalition for the Homeless officials said the policy will force homeless families to stay longer at shelters, adding, "We urge Mayor Bloomberg to halt this counterproductive policy and instead focus on providing affordable housing assistance to the growing number of homeless New Yorkers."

The Department of Homeless Services says families who do not pay rent could be asked to leave a shelter but they can contest the rent through a state hearing.