Young employees who take advantage of the government's tax- deferred thrift savings plan can have $1 million or more in their accounts by the time they retire. Older employees can also build up large cash accounts by participating in Uncle Sam's super-version of a 401(k) plan. The sign-up period for the thrift savings plan starts Thursday.

Next year, all employees will be free to earmark their payroll deductions for the stock, bond or treasury options of the savings/investment program. Now, most investments are limited to the super-safe treasury securities option.

Employees under the old Civil Service Retirement System can invest up to 5 percent of pay in the thrift savings plan. Those in the newer Federal Employees Retirement System can put up to 10 percent in (or a maximum of $7,979 this year) and get a tax-deferred 5 percent match from the government.

Workers in the new pension plan who contribute nothing to the thrift savings plan still have accounts to which the government contributes 1 percent of salary.

Plan managers say a 20-year-old worker paid $26,000 a year who invests 5 percent of pay (at 7 percent interest) will have $822,900 by age 65. Those who are paid more or invest more could easily be millionaires when they retire.

Those who leave government before retirement can continue to defer taxes by putting the money into individual retirement accounts.

A 30-year-old worker paid $26,000 who makes the same investment would have $390,000 at age 65. The figure would be much more for a worker who is paid more or invests more than 5 percent of pay.

A 40-year-old paid $26,000 a year who invests 5 percent of pay at 7 percent interest would have $175,760 at age 65.

Tomorrow at noon on WNTR radio (1050 AM), Tom Trabucco of the thrift savings plan will talk about the new investment options available to employees.Job Sharing

Yesterday's item about the new job-sharing program didn't make clear that the telephone hot line will put people interested in job sharing in touch with each other but will not inform them of job openings.

Callers will get the names of others in their grade and job series who want to work out job-sharing arrangements.

Agencies can use the Office of Personnel Management hot line to get in touch with people interested in job sharing. The number is 202-606-2700.

Tomorrow at noon on WNTR radio, Ellen Russell, of the Office of Personnel Management, will talk about the job-sharing program and answer questions from callers.Executive Job Security

The Senior Executives Association is having a members-only luncheon Wednesday at the Touchdown Club to brief executives on the recertification process that begins in January. The recertification program is linked to big raises due senior executives next year. For reservations, call the association at 202-535-4323.