A couple of milestones on the current calendar seem likely to pass without much celebration among American taxpayers.

One is the 75th anniversary of the federal income tax, which was created in 1913 by the 16th Amendment to the Constitution.The other is "tax freedom day," a calculation created and popularized by the Tax Foundation, a non-profit research organization in Washington.

According to the foundation's economists, this year "the average American would work from Jan. 1 through May 4 to furnish federal, state and local tax collectors with the funds to pay all taxes, if every cent earned from the first of the year went for taxes.

"On May 5, Americans finally start working for themselves."

As it happens, May 5 is the latest date for "tax freedom day" since people began keeping records on this sort of thing. Counting the extra day in February that comes in a leap year, it extends two days past 1987's May 4.

Not all the tax money comes directly out of consumers' pocketbooks or paychecks. Half the Social Security tax, for example, is nominally paid by employers rather than employees.

But the Tax Foundation counts the full amount, reasoning that "sooner or later, the American `worker' ultimately pays the total tax burden including business taxes, which are passed on to individuals in his or her capacity as an employee, proprietor or investor."

Psychologically, the timing of tax freedom day 1988 is unfortunate, coming just on the heels of the unpleasant surprises many people got in April as they settled their accounts with Uncle Sam for 1987.

When he saw the bottom line on his return, Raymond F. DeVoe Jr., a professional financial analyst, recalls thinking: "This can't be right. We were supposed to have reform!"

Many commentators see a special irony in the Tax Foundation's computations for 1988, the last of the eight-year presidency of Ronald Reagan. After all, Reagan came to office on a wave of tax-cutting hopes and promises.

But as the foundation notes, the tax reductions of 1981 have been steadily whittled away by a parade of subsequent changes.

It observed, "The U.S. taxpayer has now lost all the ground gained through the major cuts of the Economic Recovery Tax Act of 1981."

With subsequent rule changes and increases in Social Security taxes, it says, "like the Cheshire cat in `Alice in Wonderland,' nothing remains but the smile."

The frustration, of course, is compounded by the realization that the tax payments being made do not come close to covering the cost of government, as reflected in the budget deficit.

Sheldon Jacobs, publisher of a mutual-fund advisory letter, suggests that beyond what you have paid, "You owe the Treasury $18,569.10. That's every taxpayer's portion of the national debt."

Forecasts abound of further moves to increase federal taxes in the next year or two as the government struggles to get the budget under control.

If the tax burden is mounting, that would seem to put added emphasis on careful tax planning for those on whom it falls. But, again thanks to tax reform, some of the familiar tools used in that planning are no longer of much use.

When the accounting firm of Laventhol & Horwath examined a sampling of 1987 returns it prepared for clients in four large cities, it found that less than 5 percent made contributions to individual retirement accounts.

The tax deduction for those contributions has been reduced or eliminated for many middle- to upper-income taxpayers.

All this is enough to prompt observers like DeVoe and Jacobs to take a nostalgic look back at the first year of the income tax, three-quarters of a century ago. The tax rate for all but the wealthiest Americans was 1 percent, and more than 99 percent of the populace had to pay nothing at all.