Sometime late Monday night, when you're struggling through your labyrinthine federal tax return, it may provide some malevolent pleasure to know that Form 1040 is an endangered species.

Recognizing that most big tax-preparation firms and millions of individuals are using computers to figure their taxes, the Internal Revenue Service has a research team working on ways to create an electronic tax return that a taxpayer can file directly from his computer into the IRS computer banks.

IRS research analyst Bernard Radack says electronic filing could begin on a limited basis next year.

Direct computer-to-computer filing would eliminate the paper middleman -- Form 1040 and the dozens of other forms and schedules that taxpayers send in each spring -- and ease a clerical burden that is smothering the IRS.

Each year the agency hires thousands of temporary workers to check each return and type the data, digit by digit, into computers.

"The preparer now takes it out of a computer and prints it on paper, and then we take it off the paper and put it back into a computer," Radack said. "We're hoping we could replace the manual process if we received floppy disc or tapes that we could read directly into our computers."

The IRS estimates that about 10 million of the 100 million individual tax returns it will receive this year are being prepared on computers.

"The technology is definitely there," said Gerald Padwe, national director of tax practice for Touche Ross & Co., a major accounting firm that prepares "many, many thousands" of tax returns each year.

"It won't be in the next two or three years," he said, "but it would not surprise me if within the decade a significant portion of returns were being filed electronically."

The spread of personal computers into millions of homes and offices has spawned services and software that computerize the annual chore of completing a tax return.

There are at least a dozen software programs for personal computers that compute an individual's income tax. Most of the best-known tax-help books, such as J.K. Lasser's "Your Income Tax," also are available in software form.

IRS forms already are being replaced. The IRS has approved computer programs that print facsimiles of the tax returns, an easier chore to automate than filling in the blanks on the official IRS forms.

The movement toward electronic returns still faces a seemingly mundane obstacle that the microelectronic wizards have yet to solve. Every tax return must bear the taxpayer's signature, but how do you sign an electronic return?

"That's one of our big questions," Radack admitted. "One answer is that if the taxpayer sends in a floppy disc, he could sign a short form and stick it in the same envelope."

To the IRS, the prospect of a paperless tax return is really just a way station along the route to the government's real goal: a returnless income tax.

The Treasury Department's new tax reform proposal, released last November, noted that "the IRS is proceeding to develop a return-free tax system."

"Under such a system the IRS would, at the election of the taxpayer, compute the tax liability of most taxpayers based on withholding and information reports," the report said. "Institution of a return-free tax system could eliminate the actual filing of a tax return for . . . more than half of all taxpayers."