More than 76 percent of the government's 1.2 million retired civil servants voted for Ronald Reagan primarily because he promised not to tamper with their pension system, according to the National Association of Retired Federal Employees. President Carter and independent John Anderson lost the retiree vote partly because they backed changes in the formula that gives U.S. retirees cost-of-loving raises every six months.

NARFE, biggest of all federal-postal groups, asked its 425,000 dues-paying members whom they voted for and why. It tabulated the first 10,000 replies. They showed that 76.3 percent said they voted for Reagan, 18 percent for Carter and only 4.3 percent for Anderson.

Just before the election Reagan wrote NARFE leaders pledging opposition to White House-generated legislation that would have limited U.S. retirees to a single COL raise each year. (In response to a column last spring on the COL issue, more than 68,000 retirees and workers wrote The Washington Post. The vast majority said they opposed any COL cutback, as might be expected. Better than 80 percent said they would vote against Carter and any congressional candidates who favored limiting retirees to one raise a year. Congress eventually backed off its plan to scrap one of the retiree raises after taking heat from the retirees.)

Politicians are acutely aware of "gray" power these days. Retirees are very active in politics, especially in the rapidly growing sunbelt states. And so-called senior citizens have a higher turnout at the polls than any other age group. In addition to the 1.2 million retired federal workers, there are 427,000 widows and widowers of retired U.S. employes, plus 1.5 million military retirees and survivors who benefit from the twice-yearly COL adjustments.

Congress and the Reagan administration may seek savings in major federal programs, including reduced federal pay raises and an increase in the retirement age for government workers. But any politician who angers the former government workers is likely to become one himself.