Starting next year, career members of the Senior Executive Service will be eligible for cash bonuses of up to $14,460 under legislation the president is expected to sign shortly.

The enriched bonus system for the 6,000 senior civil servants was part of an omnibus bill approved by Congress Wednesday. Maximum raises for 100,000 managers and supervisors under the merit pay system, and survivor pension benefits for ex-spouses of government employes were also included in the legislation.

The SES pay changes would go into effect 90 days after they are signed into law. The new performance-based reward system for managers and supervisors will be reflected in mid-1985 pay adjustments.

Salaries for SES members next year will range from $61,196 to $72,300. The legislation provides for bonuses for an unlimited number of executives, based on their performance ratings and available funds, ranging from 5 percent to 20 percent of salary.

The legislation also provides a bonus "rollover" feature to get around the ceiling on total compensation that career workers can get in one year. In 1985 that maximum will be $86,200. Any executive whose total pay plus bonus exceeds the pay maximum in any one year will be allowed to receive the rest of the bonus the following year.

Until now many executives received only part of the bonuses awarded them, or portions of special $10,000 and $20,000 presidential rank awards, because of the salary maximum.

Pay for other career civil servants not affected by the omnibus legislation will go up next year to a maximum of $67,800 when an across-the-board raise of 3 1/2 percent goes into effect for white-collar workers.

Retired federal workers (and persons under Social Security) will get a cost-of-living adjustment in January based on Consumer Price Index data that will be released later this month. That inflation adjustment is expected to amount to a little more than 3 percent.