Washington — This is the week when the word ''deferral'' springs into the headlines as the latest catchword in the continuing struggle between President Reagan and Congress over the 1982 budget.
So far Congress has failed to pass a single appropriations measure, which means that no department or agency of government has a 1982 budget.
Without an approved budget, government operations could not have been paid for beyond Oct. 1, when fiscal 1982 began. Congress, however, passed a 50-day ''continuing resolution,'' allowing programs to grind on until Nov. 20.
This gave lawmakers and the President time for another round in their wrestling match over how much money the government should spend, and for what programs, in the current fiscal year.
Mr. Reagan - anxious to keep the 1982 budget deficit from swelling beyond his latest $43.1 billion target - wants to use the 50-day period to trim spending on his own.
He would instruct most government agencies to limit their spending prior to Nov. 20 to the levels he proposed most recently to Congress - namely, 12 percent below his original proposals of last March.
This tactic, called deferral, would clip at least $1 billion from fiscal 1982 spending and perhaps more, if Congress has to pass another continuing resolution beyond Nov. 20.
This week, said a key official of the Office of Management and Budget (OMB), Congress will begin getting a blizzard of more than 500 deferral requests, sent up in two or three batches.
To many senators and congressmen, including some Republicans, this tactic throws sand into the gears of orderly budgetmaking for several reasons:
* Deferral sounds like a backdoor way to strip Congress of its constitutional right and responsibility to set spending totals.
* Reagan's deferral proposals would cut outlays for many nondefense programs below the levels Congress intends.
* Trying to cope with more than 500 deferral requests would distract Congress from the job, already far behind schedule, of appropriating funds for 1982.
No one disputes the President's right to request deferrals - despite House Speaker Thomas P. O'Neill Jr.'s characterization of the tactic as a ''backdoor method to frustrate the law'' - because deferral was authorized by the Budget and Impoundment Act of 1974. Either House or Senate can kill a deferral request by simple majority.
The whole [TEXT ILLEGIBLE] March, when newly inaugurated President Reagan scrapped Jimmy Carter's tentative 1982 budget and sent his own numbers to Congress.
Mr. Reagan proposed $48.6 billion worth of budget cuts, a figure lost in the shuffle of subsequent events but still very much in the President's thought.
Working with the Reagan numbers, Congress and the White House finally agreed on $35.2 billion in spending cuts for 1982. The White House accepted this, although it was considerably less than the President had wanted.
Mr. Reagan flew to California for a month-long August vacation. Before long, his top aides warned him that things were not working out as planned.
High interest rates were adding billions of dollars to 1982 outlays and some congressional committees were appropriating a lot more money than the $35.2 billion package had called for.
All this threatened to balloon the 1982 deficit and jeopardize Reagan's goal of balancing the federal budget in 1984. More cuts, lots of them, said OMB Director David A. Stockman, would have to be made.
Adding urgency to the task is a marked slowdown in the US economy, indicating that the Treasury will collect smaller tax revenues than the White House had counted on.
So, on Sept. 24, Reagan proposed an additional $13 billion worth of spending cuts in fiscal 1982, to come mostly from nondefense programs. In essence, this would slice outlays 12 percent below the levels he suggested in March.
To implement these cuts while Congress dallies, so to speak, the President proposes to hold outlays - during the period of the continuing resolution - to his stringent goals. Republican leaders indicate that many lawmakers of their party, as well as Democrats, may desert the President this time around, refusing to trim social programs as deeply as he wants and perhaps cutting more from defense than the President proposes.