Government budget and policy brass say agencies will have little trouble coming up with the extra $800 million to finance a 7 percent federal-military pay hike next month.

The $800 million represents the difference between funds President Carter budgeted for a 5.5 percent raise and the price tag of the 7 percent boost he finally okayed. The extra funds also include anticipated costs of giving blue collar workers 7 percent raises, instead of holding them to 5.5 percent.

Each 1 percent jump in the federal-military payroll costs between $500 million and $600 million. Agencies will absorb some of the costs. Congress will be asked to approve supplemental funds for the remainder of the extra pay costs.

Political Power: The 33 unions affiliated with AFL-CIO's Public Employes Department (PED) will make Hatch Act reform their number one legislative goal in 1980. The 40-year-old law was drawn to insulate the bureaucracy from partisan politics. It also bars federal and postal workers from taking active roles as candidates, fund raisers or managers in partisan campaigns.

Many federal and postal unions believe the only way they can develop the muscle to protect pay, pensions and other benefits is to plunge openly into politics. Although some member unions may go their own way, PED leaders say a kind word from a candidate about Hatch Act reform would deliver a lot of important union endorsements. Many are waiting to hear what the man from Massachusetts thinks about Hatch Act changes.

PED winds up its convention here today.

Postal Parking: Most of the nation's 600,000 postal workers will continue to get free parking if they are covered by union contracts that specify parking benefits. Employes and officials in offices where there is no contract covering free parking will begin paying later this year when the federal free parking program ends.

Senior Executive Service: The Classification and Compensation Society is still taking reservations for its Sept. 20-21 seminar on the SES. It is geared for personnel people. Top officials from the Office of Personnel Management will be on hand to explain the new executive rating systems. Featured speakers will be OPM's Sally Greenberg, the godmother of the SES. Place is the Key Bridge Marriott. Price is $100 for society members, $125 for nonmembers. Call Mary Gwinnup or Patti Kinder at 692-8476.

Bond Boycott: American Federation of Government Employes says it will keep urging its 300,000 members to boycott U.S. Savings Bonds until pay restrictions are removed from federal blue collar workers. Although President Carter has authorized a 7 percent white collar-military pay raise, federal wage board workers are still under 5.5 percent pay raise guidelines imposed by Congress.

New Members: The Democratic leadership has filled three vacancies on the House Post Office-Civil Service Committee. It handles most federal personnel legislation. Assigned to the committee are Reps. Mary Oakar of Ohio, John J. Cavanaugh of Nebraska and Gus Yatron of Pennsylvania. The committee now has 16 Democrats and 9 Republicans.

FBI Director William H. Webster will talk to the Federal Investigators lunch meeting Sept. 20. It is at the Fort McNair Officers Club. Call FIA at 347-5500 for reservations.

Combined Federal Campaign: The government's big, one-shot charity fund-raiser will be launched today. Agency aides designated to run the campaign will meet this morning (10 a.m.) at the Departmental Auditorium. Somebody big from the White House is expected to be there.

Are Our Leaders Accountable? An excellent question, and one that will be tackled by panelists from federal and local government offices and the press. The 8 p.m. meeting is at the Alexandria Ramada Inn, sponsored by the Northern Virginia Chapter of American Society of Public Administration. Admission is free. Cash bar afterward.

Writer-Editor Jobs: Federal Deposit Insurance Corp., has openings at grades 5, 7 and 9. It also wants a Grade 4 or 5 clerk-steno and needs computer programmers at GS 5 through 11. Applicants need CS status or rating notice. Call 389-4671.