After two years of almost continuous tax-writing, a number of key players in the bureaucracies of the Treasury Department and Internal Revenue Service are jumping ship--most into more lucrative jobs in private practice--and the filling of key posts has become a game of musical chairs.

Earlier this year, David G. Glickman, deputy assistant Treasury secretary for tax legislation, left the post to return to Dallas, where he went to work for the law firm of Johnson and Swanson.

In the interim, his job has been filled on an acting basis by William McKee, whose formal title is tax legislative counsel. McKee, however, will leave the department on June 1 to become a partner in the Washington office of the Atlanta law firm of King and Spalding.

Joining McKee at the firm later in June will be Jackie Levenson, who is deputy tax legislative counsel. She will serve as counsel to the firm, a position that is somewhere between the status of a partner and an associate.

Expected to fill McKee's job as tax legislative counsel is Robert Woodward, who came to the Treasury in August, 1981, from King and Spalding. Woodward is now acting tax legislative counsel.

King and Spalding, considered to be the establishment firm in Atlanta, had strong ties to the Carter administration. The firm plans, however, to continue expanding its Washington office during the Reagan years.

Treasury's tax legislation section is widely considered to be an ideal training ground for lawyers planning to go into private practice, specializing in tax issues. One staff attorney, David Keyser, intends, however to leave to go into academia, taking a post on the faculty of the University of Texas.

Just as all these players are shifting at the Treasury's tax legislation section, Kenneth Gideon, chief counsel of the IRS, has also announced plans to leave the government.

A spokesman for the IRS said Gideon refuses to say what his plans are, although the expectation is that he will return to the Houston law firm of Fulbright and Jaworski.