Senate-House conferees begin work on a budget-cutting compromise package today that could affect the annuity checks of 100,000 federal, postal and military retirees here. One proposal the conferees will consider would force the country's 3 million U.S. retirees to forego a cost-of-living raise due them next March.

If you are against the idea of anybody tampering with your COL system, this would be an excellent time to let your elected officials on Capitol Hill hear from you. The Capitol telephone number is 224-3121.

Conferees representing half a dozen Senate and House committees will hammer out the so-called budget reconciliation package, which goes by the identifying number H.R. 7765. The COL cutback is one option they will consider.

The Senate already has voted in favor of eliminating the March COL raise. It would give retirees a full catch-up with inflation but not until September 1981. The House is on record as favoring two COL adjustments each year.

Best hope for keeping the twice-yearly pension adjustment comes from conference committee members who will represent the two "jurisdictional committees" -- Governmental Affairs in the Senate, and Post Office-Civil Service in the House -- on the panel. They are generally, but not 100 percent, in favor of keeping the March and September adjustments. They are the people who have been heavily lobbied by military groups, postal and federal unions and the National Association of Retired Federal Employes.

Conferees from othe committees, including the Senate and House Budget Committees, believe the retirees should skip one of the upcoming COL's as their contribution to the balanced budget -- which is, by the way, no longer in danger of being balanced.

An effort will be made to go with the Senate plan to skip the March raise.

So if you are interested in the COL issue -- either for or against the twice-a-year adjustments -- the time to stand up and be counted is now. Today. Preferably before the 3 p.m. committee meeting time. If the telephone lines are busy you will know you aren't the only one who cares. It is important to let Congress know it, too.

Key conferees to contact are senators Ribicoff (D-Conn.), Glenn (D-Ohio), Pryor (D-Ark.), Stevens (R-Alaska) and Percy (R-Ill.) Important House conferees are Reps. Hanley (D-N.Y.), Udall (D-Ariz.), Bill Ford (D-Mich.), Spellman (D-Md.), Derwinski (R-Ill.) and Taylor (R-Mo.).