The federal government's 1.4 million white-collar workers are due a 21.5 percent catch-up-with-industry raise this October, according to a draft report prepared for President Reagan by the secretary of labor, and the directors of the Offices of Management and Budget and Personnel Management..

Their 27-page report, which will not be released or become official until the president clears it, says that salaries of Uncle Sam's professional, clerical and technical workers lag anywhere from 17 percent to 36 percent behind pay for similar jobs in industry.

According to the salary match-up, a Grade 5 civil servant is paid about $13,369, or $2,000 a year less than his private industry counterpart. Employes in executive-level jobs who now get $63,800 would be earning more than $106,000 at the same level of responsibility outside government.

In their report, Secretary Raymond Donovan, OMB Director David Stockman and OPM Director Donald Devine said that while they support the concept of equal pay between government and industry, the present measuring system "needs modification."

The Reagan administration favors a "total compensation" system that would measure the value of pay and fringe benefit packages in government vs. the private sector. It believes that would result in fairer comparisons, and mean lower raises for U.S. workers in future.

Donovan, Stockman and Devine made the report as required by the federal pay act. That law says U.S. white-collar civilians should get pay adjustments each October to keep their salaries on par with nonfederal workers doing the same work.

Early each year the Bureau of Labor Statistics surveys wages in approximately 3,300 firms and matches pay rates for about 25 occupations in those companies. It compares rates paid them against salaries for U.S. workers in several hundred occupations within the government's 18 grade pay system. Starting salary for the lowest white-collar federal worker in Grade 1 is $8,676.

The average white-collar civil servant in the metropolitan Washington area now gets about $28,000 a year, according to the OPM.

When the annual BLS survey is finished, the information is sent to the president's pay agents--Donovan, Stockman and Devine. They in turn come up with a statistical report, and determine the so-called comparability figure, which is the percentage needed to keep U.S. worker pay levels even with industry. Their report with that comparability pay figure is then sent to the president.

The president can accept the recommendation or reject it as being too costly or out of line. In that case he can send an "alternate" plan to Congress recommending a lower percentage increase, or no raise at all.

That alternate plan goes into effect automatically Oct. 1 unless either the Senate or the House rejects it. If either body overrules the alternative plan, the higher comparability figure then becomes the amount of the pay raise.

(That system, allowing one body of Congress to overrule the president, may be out the window because of the recent Supreme Court decision declaring the so-called legislative veto unconstitutional. Lawyers in the executive and legislative branch are still studying the decision's meaning and impact).

In 1982, the report of the pay agents said that U.S. workers should--according to the BLS data--get a raise in excess of 18 percent. Reagan rejected that higher figure and proposed a 4 percent raise which is what U.S. employes got.

Other presidents--Nixon, Ford and Carter--have also rejected the catch-up-with-industry raises determined by the BLS study and the presidents' agents. They argued that the BLS study is too narrow because it does not match up federal fringe benefits with industry pay packages, nor does it include salaries paid 12 million state and local government workers whose jobs, in many cases, are closely related to those in the federal government.

President Carter asked Congress to adopt a new pay-fringe measuring system, but it ignored his request.

Reagan administration officials say that if the wage-fringe package comparision had been used, federal workers would be due a pay raise of just under 4 percent.

Earlier this year President Reagan said he would propose skipping the October pay raise for federal workers. Congress, in its first (nonbinding) budget resolution approved a 4 percent pay raise effective Jan. 1, 1984.

In recent weeks Reagan administration officials have given serious consideration to recommending that the pay raise be delayed until April 1, 1984.

But insiders think the White House will go along with any pay date Congress sets provided the amount of the raise does not exceed 4 percent. Congress will not settle on a date until mid-September when it returns to complete work on the budget reconciliation bill.