Homeowners and investors who truly want to comprehend the Capitol Hill tax-reform debate over real estate this summer need to be equipped with an advance program guide to the proceedings.

Since the preliminaries to the main event already are under way, here are three practical pointers to help you separate real estate reform rhetoric from reality:

Guideline Number One: "Grandfathering" and "transition provisions" will be the real keys to the tax bill's impact upon you, and no one on Capitol Hill has the foggiest notion yet what they'll be. The 461-page tax package that President Reagan sent Congress brimmed with bold "effective dates" for its dozens of reforms. But the package offered hardly any clues about the inevitable transition rules and phase-in periods that will be necessary to cushion taxpayers -- and elected politicians -- from the shocks of abrupt tax changes.

Take, for example, the issue of state and local taxes. The White House proposes that as of Jan. 1, 1986, all local and state property taxes cease to be deductible for federal income-tax purposes. That's ominous-sounding for homeowners whose write-offs of local property levies are important to their ability to afford their homes.

Those owners, however, shouldn't fret. The likelihood of a January 1986 effective date making it through the legislative meat grinder intact is minuscule. With $33 billion in tax revenue shifts at stake in the first full year of such a change, there is no way that the nation's cities, counties and states could live with the Reagan proposal in its present form.

Local jurisdictions have depended upon federal deductibility of their taxes for decades. They know that if homeowners are barred from writing off local taxes, they will insist on lower property-tax bills -- thereby threatening one of the traditionally richest revenue sources for most municipalities. At the very least, state and local political leaders are likely to convince Congress to postpone the 1986 effective date for a long time, perhaps via a phased-in transition arrangement extending into the 1990s.

Transition and grandfathering language is inevitable as well on bread-and-butter real estate issues such as capital-gains revisions; elimination of cut-rate, tax-exempt financing for moderate-cost homes and apartments through popular local "housing bond" programs; the extension of standard depreciation schedules from 18 to 28 years; and elimination of investment tax credits for renovations of historic and older commercial properties.

The true real estate victors in tax reform on Capitol Hill may be those who supply the transition-rule language to Congress, and get themselves grandfathered -- untouched by whatever changes are finally adopted.

Guideline Number Two: For every major federal revenue-producing reform you see stripped from the tax package this summer and fall, add at least 12 months to the likely date of passage for any comprehensive federal tax-reform law. If lobbyists for any potent interest group -- state and local governments, for example -- successfully knock out a chunk of the package designed to raise $1 billion per year or more, the Reagan reforms will all be delayed.

That's because the tax package in its current form is highly vulnerable to attack on deficit-raising grounds. By lowering brackets for individuals and corporations, the package turns into a big net money loser when any of its integral revenue-raising elements are disturbed -- like state and local tax deductions, investment tax credits and other real estate-related reforms.

Knock one of them out, and the whole bill spurts red ink. Congress may be interested in simplifying the tax code, but not at the cost of making the $200 billion annual federal deficits worse.

Guideline Number Three: Don't let the possibility of tax reform in 1986 immobilize you in 1985. Under any imaginable legislative scenario, whatever real estate sales, acquisitions or financings you carry out in 1985 should be safely grandfathered under the new law.

Make hay, as they say. And don't automatically assume that true tax reform is coming in 1986, either. If Congress holds to its legislative tax patterns of the past, comprehensive reform could easily be two or three years away, not six months.