President Carter yesterday authorized a new six-step pay scale for federal executives that will mean October increases of up to $5,800 for some.

Most of the so-called supergraders in Grades 16 through 18 of the career and political service now are frozen at $47,500. If Congress, as expected, allows the ceiling to rise to the new levels suggested by the President, pay would range from $44,756 for beginning executives to $52,800. More than 10,000 government officials, most of them working here, would benefit from the pay rise.

The increases would go to all supergraders. But those who volunteer for the new high-risk, high-reward Senior Executive Service are expected to be the biggest financial gainers Typical raises for supergradelevel federal executives this fall will move them up to $50,100.

The new pay scales are part of the private-industry style financial and fringe benefit package the Carter administration is using to persuade skitish top federal bureaucrats to enter the SES.

Under the civil service reforms enacted by Congress last year, incumbent supergraders will have until July 13 to decide whethe they want to enlist in the SES, or remain in their present GS (for "general schedule") jobs. Those who stay outside the SES are unlikely to be tapped for promotions or bigger and better jobs. And they will not be eligible for big cash bonuses, pay raises and paid sabbaticals at which SES members who do well will have a shot.

Federal agencies currently are identifying for the Office of Personnel Management (OPM) which management jobs they think should become part of the SES. Once the Senior Service is functioning, newcomers to those grade levels will be required to join it. They will be put on one-year probation, and like career employes who elect to come into the SES, will be subject to removal from the elite corps for mediocre or poor performance.

The SES law also permits the government to give career executives (but not political appointees) a handsome set of bonuses at which to shoot. For instance, up to 5 percent of the SES's career work force each year can be given the title "meritorious executive," which carries a bonus of $10,000. Those named "distinguished executives" (1 percent of the total career work force) will be eligible to get $20,000 bonuses.

SES members also will be eligible for paid "development sabbaticals" lasting up to 11 months, and will be able to accumulate annual leave (vacatione without any ceiling.

The October pay raises are dependent on Congress lifting the appropriation ceiling, which now forbids career federal workers from earning more than $47,500. According to government data based on private industry levels as of last October, long-service Grade 16 workers now should be getting $49,608. Grade 18 employes -- also frozen at the $47,500 level would have to make $61,449 to be comparable with industry.

Administration officials are guardedly optimistic that Congress will allow the pay lid to be lifted along lines the President will suggest. Since the Senate and House over-whelmingly approved civil service reform, and the concept of the Senior Executive Service, the betting is that it will allow frozen supergraders some pay ralief.

Meanwhile, administration officials are waiting to see how many supergraders volunteer quickly for the SES. A lot of the top-level career people are suspicious of it, since it does provide for easier removal and the prospect of more transfers. That sort of thing -- unless administered by very wise saints -- raises the possibility that politicians can manipulate the top ranks of the career bureaucracy easier than at present.

White House sources are betting that the financial and fringe lures of the SES, the challenges it offers and the stigma of staying out will convince most eligible employes to sign on by the July decision date.