Pretend for a moment it is next April 1, and you are the District of Columbia's budget director.

On that date, unless Congress straightens things out in the meantime, you will surely regard yourself as the innocent victim of a particularly distressing April Fool's Day prank, a sort of budgetary Catch-22 in which all or part of four years of budgets will be limbo at one time.

For you are preparing to distribute guidelines to all D.C. department heads for requests they must submit to be included in the city's budget for the 1980 fiscal year, which will be adopted by the City Council next fall and transmitted ultimately to Congress.

Ordinarily, these budget requests would be based upon the budget for the 1979 fiscal year, which would be based upon the budget for the 1978 fiscal year, which in turn would be based upon the budget for 1977.

But the District does not yet know the full amount of its budget for 1977.

It doesn't have a budget for fiscal 1978, which began on Oct. 1. And if it doesn't ever get a budget for 1978 it may have to change the budget requests it already has prepared for 1979. If that happens, the budget guidelines for 1980 - the ones soon to be prepared for distribution next April - may prove to be inoperative.

All this comes courtesy of a Congress that last year commissioned an audit report that the District of Columbia's books to be in disarray, and has created a special commission to put them back in order - at a cost of $3 million a year.

But let's go back to the beginning and see how the District of Columbia arrived at a situation where it can expect so many budgets to be hung up at one time.

The District, unlikely any other American city, is treated for budgetary purposes like a federal department. Its budgets are reviewed by the White House and enacted by Congress.

However, unlike federal agencies, the District must propose a balanced budget, with income (chiefly taxes) equalling outgo.

Customarily the budget is sent to Congress in two chunks. The bulk is supposed to go early in the calender year, hopefully by Feb. 1, so it can be reviewed and enacted before the start of the fiscal year on Oct. 1.

Toward the end of the fiscal year, a supplemental budget is submitted that includes items that were overlooked or unforeseen the first time around. Only when it is enacted is the full year's total outlay known.

In 1976, Congress enacted the bulk of the District budget for fiscal 1977 that totaled just under $1.2 billion.

Late in the fiscal year, the city asked for a 1977 supplemental appropriation of $6.8 million, including a special payment from the U.S. Treasury of $650,000 to compensate for unusual expenses - chiefly policing costs - that the city incurred at President Carter's inauguration.

Because the request came so late, the House and Senate D.C. Appropriations subcommittees decided in September to attach the 1977 supplemental budget to the regular budget bill for 1978, then making its way through the congressional machinery.

But the machinery jammed. The House and Senate could not agree on one big item requested by the city - $27 million to acquire land for a downtown convention center projected to cost an ultimate $110 million. The House agreed, but the Senate Senate balked.

When a conference committee's deliberations were deadlocked, Rep. William H. Natcher (D-Ky.), the veteran chairman of the House D.C. Appropriations SUbcommittee, proposed a novel solution of sorts. Instead of enacting a 1978 budget, Congress would pass a so-called "continuing resolution" permitting the city to continue spending at 1977 levels, a total of about $1.1 billion for operations. It was enacted last week and signed into law by the President.

Passage of continuing resolutions for short periods - usually for a month at a time - is not unusual, pending agreements on regular budgets. But veteran congressional aides could not recall when such a resolution had been passed to cover 10 months of a fiscal year.

That's where the city is right now for fiscal 1978. If it chose, Congress could back and enact a regular budget, but there are not yet any signs it will do so. Comer S. Coppie, the city's budget director, has talked of "serious implications" for the city if there is no regular budget, but he has not spelled these out.

He said he is preparing a report on the matter for Mayor Walter E. Washington.

Talking to a reporter the other day, Coppie noted that some things proposed in the 1979 budget are built upon the foundation of the nonexistent 1978 budget. For example, the 1979 budget proposes spending a second intallment of $45 million on the convention center. It could not spend that second installment without a first installment, he said, so it is likely the 1979 budget as now proposed must be amended.

And without knowing about the fates of either the 1978 or 1979 budgets, what do you tell the department heads about preparing the 1980 budgets? That's the problem we're pretending to deal with.

Gladys Mack, deputy budget director, said a close reading of the congressional continuing resolution makes it clear that the city can pay increased salaries to its employees, even if it breaches the budget limit.

Otherwise, just about the only individual item specifically decided by Congress for fiscal 1978 is the financing of the city's Advisory Neighborhood Commissions. The outlay of $1 million for 1977 has been cut in half.