The rarefied few who can afford to shell out tens of millions of dollars for an apartment in one of the gleaming new condominiums being built across New York City may be searching for luxury, but in some cases they will find an unexpected perk: a break on real estate taxes that can mean tax bills as low as $96 a month.

At 56 Leonard Street, where a penthouse just went into contract for $47 million, the buyers are poised to receive a 76 percent break on their real estate taxes.

At 150 Charles Street, an ultraluxury development in the West Village, the tax break is 70 percent.

And at One57, the 90-story skyscraper in Midtown where asking prices top $10,500 a square foot, the tax break is an eye-popping 94 percent.

A recent review of the offering plans for some of the city’s most expensive new apartment buildings offers an interesting peak into the perquisites and disadvantages of a lavish lifestyle. There are the windfalls, like the generous tax breaks, but there are also oft-overlooked expenses, like mandatory health club and dining-room fees, that can add to a buyer’s bottom line.