SINCE NOT EVERYONE can check out or use the grounds of the snazzy country clubs in Montgomery County, many people may not realize what the members enjoy most at these places of play. It's not the 19th hole -- but a tax loophole that gives the clubs fat discounts on the county property tax rate. because of it, the county is losing between $1 million and $2 million a year or, to turn that around, taxpayers are shouldering the burden of country-club tax breaks -- in effect providing a public subsidy for the private facilities. But taxpayer relief may be on the way, thanks to efforts by some members of the country's delegation to Annapolis.

Here's how the county has been shortchanging itself: The tax breaks orginated in 1965, as a way to encourage land purchases by country clubs and thereby encourage the permanent greening of much county land. the spaces did stay green -- though not exactly open -- and the tax gap widened spectacularly. Instead of being assessed at 50 percent of market value, as commercial properties have been, Montgomery's country clubs have been assessed at about 11 percent.

Leading the charge has been a Republican legislator from the county, Del. Luiz Simmons. He is the sponsor of a state bill to eliminate the tax break altogether. The main question in the minds of his fellow county members of the legislature is how fast to stop the subsidy. A subcommitee of the county delegation has cleared a compromise in which club taxes would be increased gradually over a five-year period. This provision, introduced by Del. David Scull, would raise the rate for clubs to 40 percent by 1986.

A better answer would be somewhere between all-of-it-now and almost-all-in-five-years. Too drastic a change could cause severe difficulties for the clubs' treasuries, even though memberships of the clubs do tend to be made up of the more resource ful people in the county. But why lose too many millions of dollars because of an overly gentle catch-up rate? How about shooting for the full commercial rate three years from now? Whatever the final figures, the delegation should make sure a strong bill does emerge from the coming General Assembly session. This tax break is an idea whose time has long gone.