Life insurance policies for civil servants jumped $7.3 billion in value this month -- to $245 billion -- because of the 3 1/2 percent pay raise that went into effect. Depending on an employe's salary, the increase in the value of each insurance policy could range from $1,000 to $3,000.

Much of this month's gain in salary and life insurance would be wiped out, however, if the Reagan administration can convince Congress to cut federal salaries 5 percent later this year or early next year. If that happened, employe salaries would drop and the value of each worker's life insurance could decrease between $2,000 and $3,000.

The average federal worker now earns more than $31,000 a year, while the median (middle) civil service salary in the Washington area is about $28,000.

Basic insurance policies of U.S. workers are linked to their salaries (rounded to the next highest $1,000 amount), plus an additional $2,000.

That means an employe earning $29,999 a year has a basic life insurance policy of $32,000, while a worker earning $30,001 per year has a policy of $33,000.

In addition, employes can also buy optional life insurance, also linked to salary, of up to $78,000 a year.

Employes pay a premium of 22 cents every two weeks for each $1,000 of basic life coverage. Federal officials say that Metropolitan Life Insurance Co. is the primary insurer for the U.S. program, although the actual liability is spread out to more than 200 other insurance carriers.