When critics complain about "loopholes" in the federal income tax system, their horror stories usually involve tax breaks that benefit either the rich or the large corporations. The list is a familiar one: Big oil. The airline industry. A small firm in Pittsburgh. Doctors who invest in condominium projects.

The detractors are right, of course. Those kinds of tax breaks emerge from Congress with disquieting regularity, and often they do provide special treatment for the privileged that ordinary taxpayers don't get. Sometimes, these can be defended on economic grounds. in other cases, the justification in awfully hard to see.

But despite such conspicuous lapses, statistics show the bulk of the revenue the government loses from tax breaks actually goes to benefit the broad masses of Americans, who consistently have been up in arms whenever tax purists have suggested repealing any of these provisions.

Indeed, of the so-called Top Ten tax "loopholes" -- at least in terms of billions of dollars of revenue cost -- only three involve tax breaks that primarily benefit high income persons or big corporations. And the one affecting companies ultimately is passed on in new jobs and lower inflation.

These conclusions come from an interesting -- and eye-opening -- list of "tax expenditures" that the government has begun establishing each year as part of the federal budget. In effect, the list is a breakdown showing all the big tax breaks and how much they "cost" in terms of lost revenues.

The "tax expenditures" concept is a simple one: If spending programs can be measured on the basis of how much they cost the government, so can tax breaks. If by enacting a special deduction for disabled coal miners the governement will take in $50 million less, then the proposal effectively "costs" $50 million.

As in the case of spending programs, the overall "cost" of continuing these tax breaks grows each year with the size of the economy. In fiscal 1980, the government estimates the total revenues lost from all such tax breaks will reach $168.9 billion -- up from $149.9 billion in the current year.

If all these tax breaks were eliminated, the government would take in $671.5 billion -- enough to wipe out its $29 billion budget deficit and cut taxes across the board by a massive $110.9 billion. (Of the $168.9 billion in tax breaks next year, $126.2 billion will go to individuals and $42.7 billion to corporations."

One interesting this about the fiscal 1980 figures is that by far the biggest "tax break" for individuals is one that benefits virtually all wage-and-salary workers -- the exclusion from individual income tax of employer pension contributions and pension fund earnings. The cost: a staggering $12.9 billion.

To be sure, two of the largest tax breaks on the list once again involve the special tax treatment for capital gains, which benefits high-income persons the most. Capital gains are the profits from the sale of stocks or other assets. Congress cut capital gains taxes sharply last year.

And a third provision deals with allowing businesses an investment tax credit when they buy new machinery or equipment to modernize their production facilities. The increased capital spending, however, is designed to boost productivity and create new jobs. In the long run, that benefits workers as well.

(In fiscal 1980, the revenue loss from allowing a special tax break for capital gains is estimated at $10.2 billion. Not taxing capital gains at the time the investor dies deprives the government of$10 billion. And the investment tax credit for business amounts to $15.3 billion.)

But the others on the Top Ten list -- such as the exclusion for pension contributions and earnings -- go to broad numbers of Americans. Nothing on the corporate side of the listing compares in magnitude with the size of these breakes for individuals.

The rest of the listing -- in order of cost to the treasury -- includes:

$12.5 billion to allsow individuals to deduct their state and local taxes (other than property and gasoline taxes) -- a tax break dear to the hearts of most Americans. President Carter briefly considered chipping away at this break last year, but was rebuffed soundly after voters protested to Congress.

$9.6 billion for the exclusion of employer contributions for medical insurance premiums and medical care -- actually a form of income, since workers otherwise would have to pay for the coverage. Carter also tried to cut this back last year, but Congress again declined even to consider it.

$9.3 billion for the deduction by homeownrs of the interest paid on their mortages.Carter mentioned this once during the 1976 presidential campaign as a "loophole" he would be sure to propose closing. But he backed away almost immediately amid a storm of protest from voters.

$6.6 billion for the deduction convering local property taxes on private homes. Although this break is allowed without limit for home-owners, it's not available for apartment-dwellers, who also pay property taxes -- indirectly -- as part of their rent. Some experts have questioned this disparity in a time of high house prices.

$6.4 billion for allwoing Social Security recipients to escape payment of taxes on their old-age and survivors' insurance benefits. So cial Security benefits have been tax-free from their inception, but they still are a form of income that without this provision would be subject to tax.

$6 billion for allowing a deduction for charitable contributions -- a writeoff questioned by some tax experts, who view it as a sop to private fundraisers that does little to encourage everyday giving in all but the very high income brackets. Carter fought an expansion of this writeoff last year.

By contrast, the more controversial "loopholes" the critics often cite are relatively modest. The widely criticized tax subsidy for exporters (under the Domestic International Sales Corporation program) costs $1.3 billion. Deferral of taxes on foreign-source income "costs" only $445 million.

The listing doesn't really take away from the separate complaint by critics that Congress still passes too many new "loopholes" that benefit the privileged or certain narrow-interest groups. But it does show that the rich and powerful aren't the only ones upon whom the government lavishes tax breaks.

That may be one of the reasons that full-fledged "tax reform" has proved so elusive in recent years.