More than 900,000 Maryland homeowners will receive checks averaging $680 from their mortgage companies later this year as the surprising one-time ripple effect of a new law designed to reduce real estate closing costs.

Homeowners will not have to go anywhere to ask for the money, and there will be no calls to make and no hoops to jump through. According to state legislators who supported the bill, the money will just appear in most property owners' mailboxes sometime after July, when the law goes into effect, and before the end of the year.

The actual amount people receive will depend on the size of the tax bill they pay.

"I never thought we'd actually say this, but the check is in the mail," said Del. John A. Hurson (D-Montgomery).

The law, pushed by real estate brokers and passed last spring by the General Assembly, was designed to spur home sales by reducing closing costs in Maryland--now among the highest in the country. By requiring homeowners to pay their property tax in two annual installments, rather than one, lawmakers cut in half the amount of money a mortgage servicer can require home buyers to pay up front for future taxes.

Yet most of the excitement surrounding the new law centers on the unintended consequence it holds for people who already own homes in Maryland.

Under the traditional once-a-year payment schedule, most property owners were required to hand the bank about a year's worth of property tax to place in escrow when they bought their homes. But as the state changes to a twice-a-year schedule, they suddenly will have about six months' worth of surplus in their escrow accounts--well beyond the amount banks are allowed by law to hold on to.

So the banks will have to give it back--a one-time payoff that the bill sponsor, Del. Peter Franchot (D-Montgomery), estimates at more than $700 million across the state.

"It's not something that will be owed again later. It's your money," said William J. Armstrong, president of the Maryland Association of Realtors.

It's not all free money, though: State law allows counties to impose annual fees on property owners who pay on semiannual schedules--amounts ranging from $12 to $17 in the Washington area. Franchot said some counties may consider dropping the fees now that semiannual payment will go into effect for most people; however, none have done so thus far.

Homeowners can ask their mortgage companies to keep them on an annual schedule, but if so, they will not get the cash back.

State officials said they have received thousands of letters and calls about the new law. Franchot announced yesterday that he has created a World Wide Web site to answer questions about the payments, Questions also can be referred to the Maryland Association of Realtors, 800-638-6425; the state Department of Assessments and Taxation Real Property Division, 410-767-1199; and the state Department of the Treasury customer assistance unit, 800-613-6743.