Retired federal and military personnel, whose pensions are linked to the cost of living, will get larger percentage increases this year than active duty civil servants and military people whose pay is supposed to be geared to industry.

On Sept. 1, the nearly 100,000 federal, postal and military retirees in metro Washington will get their second cost-of-living boost of the year, an increase of 4.9 percent. The higher payout will first show up in monthly annuity checks mailed for October delivery to the million-plus retirees or their survivors worldwide.

On March 1, federal and military retirees got a 2.2 percent raise, based on living cost increases in late 1977.

President Carter has said he will limit the October catchup-with-industry raise for active civil service and military personnel to 5.5 percent. According to government figures, the raise should average slightly more than 8 percent. But the president has slapped a lid on the active duty pay raises as part of his anti-inflation program.

By law federal and military retirees get two raises each year - March 1 and Sept. 1 - to reflect changes in the cost of living as measured by the Consumer Price Index. Regular federal and military personnel are supposed to get one-shot raises each October designed to keep them on a par with pay changes for similar jobs in the private sector.

This year the Labor Department data showed government workers would be due an increase of about 8.2 percent on average. But the president has the power, if Congress fails to overturn it, to issue an alternate pay plan. He is expected to formally propose the 5.5 percent pay cap later this month.

The total 7.1 percent raises that retirees will get this year does not mean they are better off financially than active duty workers. Retiree pay, like that of regular employes, is taxable. And the larger percentage increases go to retirees whose monthly incomes, generally, are much smaller than active duty workers.

Retirees do not have to apply for cost-off-living raise. It is automatic, and should show up in checks they receive shortly after Oct. 1.

Convention Time: The National Association of Letter Carriers is meeting this week in Chicago . . . American Federation of Government Employes meets there next week and the American Postal Workers Union will be in Denver later this month. The National Association of Postal Supervisors opens up its convention Saturday in Milwaukee.

Life Insurance: Premiums paid by government workers for their regular salary-equivalent policies will drop beginning next month. The present biweekly rate of 53.25 cents per $1,000 of insurance will drop to 38.25 cents. New biweekly rates for the $10,000 optional insurance will last like this by age group.

Under 35, a drop from 80 cents to 60 cents, 35-39, down from $1.20 to $1; 40-44, down from $1.90 to $1.70; 45-49, down from $2.90 to $2.40; 50-54, down from $4.50 to $3.50; 55-59, down from $10.50 to $7.50 and for persons 60 and over the biweekly premium per $10,000 of optional insurance will go down from $14 to $9.00.

Postal Update: The board of governors of the U.S. Postal Service meets this morning in Portland, Ore. for a state-of-the-service report from Postmaster General William P. Bolger. USPS brass feel that strike sentiment is cooling, thanks primarily to a court order which blocked the New York Metro area union leaders from conducting a strike vote. The 500,000 rank-and-file postal employes will vote later this month whether to accept or reject the contract hammered out between their union leaders and USPS bargainers.

Clerical Jobs: National Commission on Libraries is looking for a stenographer and two receptionist-typists to work on a White House conference. Call Ms. Reszetar at 653-6252 for job details. Food and Drug Administration has Grade 2, 3 and 4 clerk-typists openings. Call Ms. Harirs at 245-1070.

Uniformed Services Almanac: The reference "bible" for active duty, reserve, National Guard and retired military personnel for 1978 is still available. An updated version for each group for next year, is in the works. It has become a standard reference for many Pentagon officials, military associations and individuals. Get details by calling (703) 532-1631.