You may be a secret winner or loser in the 1986 real estate tax-reform legislative sweepstakes. To get a clue as to how you fare, take a look at the new Senate version of federal tax reform, unveiled last week on Capitol Hill.

Tops on the winners list -- as in the legislation passed by the House last December -- are owners of first and second homes. In the midst of drastic cutbacks in investment preferences everywhere else in the tax code, American homeowners emerge with major relative advantages.

First, the deductibility of mortgage interest and property taxes for primary and second residences is cast in Capitol Hill concrete. Unlike the Reagan administration's 1985 proposals to end the deductibility of mortgage interest and property taxes for second homes, the Republican-controlled Senate Finance Committee's bill leaves current deductions unscathed.

Under the new Senate bill, you can continue to deduct every cent of your property taxes and mortgage interest for as many as two homes. Whether you own a house that racks up $5,000 in mortgage interest payments per year, or two homes that rack up $40,000, you're safe.

Your maximum personal income-tax bracket will drop to either 15 percent, 25 percent or 35 percent. You'll presumably have more after-tax cash to spend but on the other hand, you'll find the write-off value of your mortgage and property-tax payments lessened somewhat.

If the Senate bill passes in its present form, homeowners will have one of the very few personal-use tax shelters left standing in the wake of comprehensive federal tax reform. With unlimited ability to deduct interest and property levies, taxpayers will have new incentives, in fact, to buy larger principal residences, financed with larger amounts of mortgage debt, and to buy a place at the beach or the mountains if they'd never owned one.

Renters, by contrast, receive no tax advantages whatsoever under the Senate bill. To the contrary, the Senate tax legislation appears likely to create new incentives for future owners of apartment complexes to raise rents. The bill would increase many apartment developers' costs of financing by restricting the availability of cut-rate, tax-exempt mortgage-bond issues from local and state agencies.

It would stretch out residential and commercial rental real estate depreciation schedules to 30 years, up from 19 years, and thereby would raise annual federal tax bills for rental-property owners. It also would sharply reduce the ability of developers to raise capital for rental projects through their most popular current vehicle -- public and private real estate limited partnerships. Although apartment-industry trade association spokesmen say the Senate legislation in its present form could lead to rent increases of 15 percent to 25 percent over a five-year period, no one has authoritative projections.

What is certain, though, is that the federal tax-treatment disparity between renters and homeowners will be widened under the Senate bill, not lessened.

Who are the other winners and losers under the latest version of tax reform? In the winners column are: %TModerate-income first-time home buyers, and the builders and sellers of homes for such buyers. The Senate bill would preserve the popular "mortgage-bond" program used by government agencies across the country to provide cut-rate mortgage money for first-time purchasers. As much as $21 billion to $25 billion worth of such mortgages could be financed this year alone, according to Carl W. Riedy Jr., head of the Council of State Housing Agencies.

Sellers of property who were worried about higher capital-gains taxes. The Senate bill keeps the maximum federal capital-gains levy at 20 percent, down 5 percentage points from the House-passed bill.

Renovators of historic buildings who had worried about losing their valuable investment tax credits. The Senate bill provides a 20 percent credit on renovation expenses for certified historic buildings and offers 10 percent credits on renovation costs for non-historic commercial projects.

And who are the biggest losers in the proposed new legislation?

Just about anyone who invests in real estate limited partnerships. The Senate bill limits annual interest write-offs (other than for home mortgages) to $1,000 beyond "net investment income" for a single taxpayer and $2,000 to taxpayers filing jointly.

That limitation, which effectively removes one of the key traditional tax benefits of partnerships, "would just about kill real estate investments by tens of thousands of small and medium-scale investors," according to Allen Cymrot, president of KemperCymrot, a nationally prominent real estate syndication firm based in Palo Alto, Calif.

"I can't believe the full Senate would be so shortsighted as to pass the bill in its present form," Cymrot added. "It would be an absolute disaster for American real estate in general."