Federal workers and retirees who have dreaded the thought of trying to pick a health insurance plan before, during or just after their summer vacation can relax for a while.

A plan that many saw as a mid-summer nightmare, forcing people to think about health insurance during their rest time at home, the beach or the mountains, has been postponed.

The Office of Personnel Management scrubbed plans yesterday to open the federal health insurance hunting season in August 1992.

The federal health program is the nation's biggest employer-backed program. It covers more than half the people in the Washington area, and more than 10 million current and former federal workers and their families.

Last month, OPM advised health insurance plans that the current November-December open season would be replaced by an August-September open season. That would have forced insurance plans -- whose 1991 benefit proposals are due at OPM today -- to negotiate 21-month contracts instead of the normal 12-month agreement. OPM has extended the deadline for submitting new rate proposals by a week.

OPM wants to switch the insurance program from a calendar year to a fiscal year timetable. Workers and retirees now pick health plans between mid-November and early December. Coverage for them starts in January. OPM decided to have the open season start in August 1992 with coverage to begin Oct. 1, the start of the new fiscal year.

In a letter yesterday to the 400 health plans in the federal program, OPM said it wanted to avoid the cost of holding two open seasons in one fiscal year because of pending budget cuts for OPM and other agencies. If the open season switch had been made, there would have been the regular open seasons in the fall of 1990 and 1991 and another one in August 1992.

OPM officials say they still plan to put the health insurance year on a fiscal year cycle, but probably not for another three years.Job Mart

The National Institutes of Health in Bethesda needs a Grade 9 through 12 personnel management specialist. Call Cathy Richardson at 496-6895. Hatch Act

Bush administration sources predict the president will veto a Senate-House compromise bill in the works that would relax the Hatch Act. The 51-year-old law limits what federal and postal workers can do in partisan political campaigns.

The Senate version, which passed with enough votes to override a Bush veto, is much more moderate than the House plan. Backers hope the president won't see the Senate-like compromise bill as being worthy of a veto battle with the Senate. But administration sources say he is being advised to veto any relaxation of the Hatch Act because it would inspire another drive next year for more changes. Census Takers

Temporary census enumerators who had to work Memorial Day will not get holiday pay or overtime because they aren't considered to be permanent federal employees.