Within the next few weeks some of the $5 million per day that federal and postal workers now invest in U.S. Treasury securities will be shifted to the stock market.

If government workers, with an $85.4 billion annual payroll, take advantage of the new option to shift up to 20 percent of their tax-deferred investment money to two new options, it could make them, in a relatively short time, major players in the country's private stock and bond markets.

Virtually all of the government's 2.9 million employees, from secretaries to senators, are eligible to take part in Thrift Savings Plan. The savings plan is Uncle Sam's deluxe version of tax-deferred 401(k) plans available in the private sector. More than a million federal workers now have savings plan accounts and are investing from 1 percent to 10 percent of their salaries.

Money invested in the savings plan (both employee and government contributions) is not counted as income. Workers do not pay taxes on it until it is withdrawn.

The savings plan began last April. As of Friday it had assets of $1.13 billion, and is growing at the rate of about $150 million each month from more than a million workers whose contributions have earned $21 million in interest in the last eight months.

Savings plan investments last year were confined to the so-called G-Fund. It is made up of guaranteed Treasury securities whose interest rate (currently 8 7/8 percent) varies monthly.

Workers in the new Federal Employees Retirement System can invest up to 10 percent of pay (or a maximum of $7,000 per year) in the savings plan. Those who put in 5 percent or more get a 5 percent matching contribution from the government. Workers under the old Civil Service Retirement System can put in 5 percent of pay, but get no match from the government.

Starting this year workers who are under the FERS program will be able to invest 20 percent of their regular payroll contributions into one of two funds. They are the C-Fund, managed by Wells Fargo, which is designed to replicate earnings (or losses) in its own Standard & Poors stock market fund; or a so-called F-Fund made up of bonds.

Union Bites Union

National Federation of Federal Employees staff members who are represented by the Office and Professional Employees International Union picketed the NFFE's 16th Street headquarters yesterday. They are protesting alleged antiunion tactics by the union that employs them. The NFFE workers say their union refused last week to give paid time (on the clock) to a staff member who has been representing them in contract talks with their union. The protesters also say their union is refusing to give raises that would bring their salaries up to rates paid similar employees in rival federal unions.

Job Mart

Commerce is looking for a Grade 8 ($20,739 to $26,958) secretary (typing or stenography). Call Anne Gibson at 377-3301.

Commodity Futures Trading Commission needs a payroll technician, GS 5 through 7, with civil service status, and a GS 4/5 secetary (typing). Call 254-3679.

National Oceanic and Atmospheric Administration in Suitland wants a GS 5/6 secretary (typing). Call 443-8425.