Pay and pensions of federal workers and retirees are under attack on several fronts these days. Here's a thumbnail description of where the action is:

Gramm-Rudman-Hollings: This bipartisan amendment to the Deficit Reduction Act has already cost federal-military retirees the 3.1 percent cost-of-living adjustment they were due last month. Bills are pending in Congress to restore the raise. But don't hold your breath.

At the same time, the National Association of Retired Federal Employees has gone to court to argue that the COLA take-back was unconstitutional. It could be months before the issue is decided.

Starting next month, the Gramm-Rudman-Hollings amendment will force agencies to cut spending, which could translate into hiring and promotion freezes, cuts in travel and other trims. Later on, some agencies may be forced to furlough workers to avoid layoffs.

*Tax reform: The Democratic tax reform bill approved by the House would require feds retiring after July 1 to begin paying taxes on a portion of their pensions. (That date could change, because it would hit many influential members of Congress -- including House Speaker Thomas P. O'Neill Jr. -- who plan to retire next January.) The proposal would affect the pensions of millions of federal, state and local government workers who help finance their own pension plans.

Under present law, people whose pension contributions were taxed while they worked aren't taxed after retirement until they get back all the money they contributed. For federal retirees, that takes about 18 months, on average.

Federal and postal groups hope to persuade the Senate Finance Committee to exclude the House pension tax proposal from any Senate bill. Sen. Paul Trible (R-Va.) has introduced a sense-of-the-Senate resolution that, if passed, would keep the pension tax plan out of the Senate reform bill. Once the Senate passes its version, House-Senate conferees will attempt to work out a compromise.

*The president's budget: President Reagan has asked Congress to freeze pension raises next year for federal-military retirees, to give federal workers a 3 percent raise, and to require federal and postal employes to contribute 9 percent of their salaries (they now put in 7 percent) to their retirement programs.

He also has asked Congress to raise the federal retirement age to 62 and to set up a voucher system whereby workers and retirees would get a check each year from the government to buy health insurance. None of the proposals can be put into effect without Senate and House approval.

Gramm-Rudman-Hollings is here now, although few people understand what its full impact will be. The tax reform plan must clear the Senate, then get full congressional approval. Each item in the president's budget must be approved by Congress -- and that could take months, or, on the other hand, never happen.