President Carter has asked Postmaster General Benjamin F. Bailar to shield individual citizens from an anticipated rise in the cost of first class postage by issuing a special stamp, and Bailar is expected to pass on that request to the U.S. Postal Service's independent board of a governors today.

Carter wrote Bailar Thursday asking him to consider a special, lower "citizen rate" for first-class mail.

Carter's letter did not mention a figure, but one suggestion made within the White House was for a 12.5 cent stamp to be sold in books of eight for $1.

Bailar is expected to ask his board to raise the price of a first-class stamp from 13 cents to 16, but also to create a special first-class rate - perhaps 13 cents or lower - for the personal use of individuals, according to sources.

If approved by the board and by the Postal Rate Commission, those rates would probably take effect early next year.

"I believe that as a matter of national policy it would be in the public interest to pursue the concept of a citizen rate first-class postage for use by consumer," the President wrote.

"I understand that it might be possible to have a lower rate of postage to use in such correspondence, I also understand that the consumer stamp would not be used by businesses in their outgoing mail but could be used by consumers in coressponding with business."

The letter suggested that Bailar brief carter's chief domestic policy adviser, Stuart Eisenstate, and Bert Lance, director of the Office of Management and Budget, if he thought the concept feasible and ". . . consistent with the intent of the Postal Reorganization Act, including your efforts to control costs."

At least one meeting between Eizenstat's office and representatives of the Postal Service has since taken place.

Of the more than 50 billion pieves of first-class mail that the Postal Service handles every year, about 10 billion, or 20 per cent, would be expected to qualify for any new, lower rate.

The Postal Service projected a $50 million loss for the fiscal year that ended Thursday, compared to a $1.2 billion loss in the previous fiscal year.

Sources familiar with the Postal Service's rate-setting policies said, however, that a lower "citizen rate" as envisioned by the President would not cost the Postal Service any money because rates are based on what the service thinks it will need to break even, and then "rounded up" to the nearest whole cent above that.

The rounding up creates a "surplus," the sources said, that could be used to subsidize the "citizen rate."

Before Carter suggested a "citizen rate," the board of governors was expected to vote today on increased rates for all classes of mail, and they still may arrive at a decision with having to call another meeting.

The independent Postal rate Commission has 10 months in which to review whatever rate changes the diectors recommend.

Carter said at his news confernce last Thursday that he won't decide what he wants to do with the independent agency until closer White House control, ending the independence which Congress voted to give the Postal service in 1970.