The White House yesterday said that citizens, accountants and state and local government employes will have 108 million more hours this fiscal year to do something other than fill out federal forms, thanks to the war on paperwork that was launched with the 1980 Paperwork Reduction Act.

That puts the Reagan administration ahead of the three-year goal of a 25-percent reduction in the paperwork burden, according to a fact sheet released by the Office of Management and Budget with its third annual "Information Collection Budget."

OMB calculates that when Sept. 30 arrives, Americans will have gained 300 million hours (an average hour and 19 minutes a person) once consumed by such tasks as adding the totals of lines 3, 4 and 6, putting the result on line 10 and multiplying by 13.6 percent.

"This is the equivalent of 150,000 work-years spent on government paperwork each year that will now be free for more productive purposes," Office of Management and Budget Director David A. Stockman said in a letter to President Reagan.

There remains, however, considerable skepticism about these numbers among the new experts in paperwork-reduction estimates.

These bureaucrats specialize in the arcane science of counting the minutes it takes to fill out everything from income tax forms to forms telling the Interior Department how a strip miner intends to restore the land when the mining's finished.

"Paperwork estimates are an attempt at determining an average burden," an OMB official told a paperwork conference six weeks ago.

"There are extreme variations around the middle," the official said.

"If we estimate it's going to take half an hour to do something, it may take five minutes for someone, and for someone else it may take five days."

Among the forms streamlined or discarded in the latest cut:

* The Transportation Department's record-keeping requirements under the Highway Safety program, which required states to maintain records of such things as accident investigations, motor vehicle registrations and motor vehicle inspections.

Many of these requirements will be discontinued in fiscal 1983. Estimated savings: 68 million hours.

* DOT's Driver's Log, begun in 1940 to record where a truck driver's been, where he's going and how long he's been behind the wheel.

DOT proposed to eliminate the log entirely, but unions and state and local governments protested, pointing out that the federal form would be replaced by a broad range of state forms, involving more burden to large trucking concerns whose drivers crossed many state lines.

The new rule allows a variety of abbreviated forms to qualify as daily logs. Estimated savings: 11 million hours, $164 million.

* The Internal Revenue Service's Employers' Quarterly Tax Return. Data collection on this one-page form will be reduced by 33 percent.

Estimated savings: 8 million hours.