Acting Gov. Blair Lee came up a day late today in asking President Carter to veto federal legislation on that would prohibit Maryland from collecting income tax from members of Congress who live in the Washington suburbs.

While Lee was denouncing the bill today as "unconscionable," at a press conference at which he released a letter he had sent to Carter recommending the veto, the White House was announcing that Carter had signed the measure into law.

Lee wasn't the only one who was tardy in sending a message to the fast-moving Carter White House. Sen. Charles Mc. Mathias (R-Md.) issued a press release today also urging a veto of the bill. An aide said that Mathias signed the letter to Carter last week, but it wasn't delivered by hand, until late yesterday.

Mathias' letter said enactment of the bill would have the effect of forcing Maryland taxpayers "to pay for services which these elected oofficials receive free of charge," Mathias added that congressman and senators from states that have no state income tax will get a "really free ride."

One person who wasn't late in protesting was Maryland's fast-talking - and appartenly fast-writing - comptroller, Louis L. Goldstein, who sent off his protest on July 13.

President Ford vetoed a similar bill last year.

Lee said that, while he has "never had great sympathy for Maryland's taxation of these people," the legislation passed by the Congress is "outrageous" in that it calls for refunds of taxs already paid by out-of-state representatives and senators.

"In some instances, former congressmen and their estates," said Lee, explaining at a press conference his letter to the President.

The federal legislation was prompted by a complaint from Rep. Richard Ichord (D-Mo.), who was dunned by the state for 10 years in black taxes that the state claimed he owed as the result of his part-time residency in Prince George's County.TBoth the District anv Virginia waive and local income taxes for members of Congress who live in thieir juridictions, But Maryland, where about one-third of the members live, only provides a credit against taxes paid in another state.

"It's not a large amount (of money), but a very large principle is involved," Lee said.

Members of Congress who own houses in the Washington area will continue to pay real estate taxes, no matter where they live.

On another matter, Lee said he believes the state should reimburse private fees incurred by half a dozen present or former members of Gov. Marvin Mandel's staff who were subpoenaed to appear before the federal grand jury that indicted Mandel on Charges of political corruption.

Bills submitted by current and former officials ranging up to $6,000 are being studied by the Board of Public Works. The bills were submitted by Frank A. DeFilippo. Mandel's former chief of staff who now is an advertising executive handling Lee's campaign for governor, and present Mandel-Lee aides Frank Harris. Hams F. Mayer, Ronald Schreiber, Michael S. Silver and Maurice R. Wyatt.