CBO, the influential Congressional Budget Office, says it will take an October raise of 11.7 percent to bring federal white-collar pay up to industry levels. That is nearly double the 6.2 percent amount proposed by President Carter.

CBO's pay projection is part of an analysis of Carter's new budget made at the request of the House Appropriations Committee. It should help federal unions in their fight for a bigger October raise.

Carter's budget says federal employes are due a 10.9 percent "comparability" raise under the current government salary-fixing formula. But it anticipates Congress will approve sweeping "reforms" proposed by Carter, reforms that would shave the amount of the raise down to around 6.2 percent. Military personnel, under the same reform package, would get an estimated 7.4 percent raise.

Carter's pay reforms would measure the value of fringe benefits and pay in the government against those in the private sector.It also would match federal wages with generally lower rates paid state and local government employes, and link white collar government salaries on a job-by-job match-up with rates paid in hometown industries. Such a system, the administration believes, would cut back the value of annual federal pay raises that are now pegged to a nationwide formula that compares certain federal pay levels with industry, but excludes fringe benefits and salaries paid the 12 million state-county-municipal workers.

The 6.2 percent October pay proposal in Carter's budget is not solid. It could be raised -- or lowered -- either on the basis of "reform" if enacted, or modified by the president under the existing system. As the CBO report says ". . . the final pay raise would depend primarily on how the administration constructs and evaluates the nation-wide non-federal employer benefit survey."

But whatever the final figure, or the method used, CBO says the president's estmiate of the amount it would take to give federal workers October comparability with industry (10.9 percent) is short. It says it would take an 11.7 percent raise this October to meet comparability, and make up for reduced raises in recent years.