Wilbur D. Mills, who left Congress and his powerful post as chairman of the tax-writing House Ways and Means Committee in a scenario that would have delighted Hollywood script writers is returning to the tax fray as counselor Mills.

Mills will join the Washington office of the politically potent New York law firm of Shea, Gould, Climenko and Casey within the next few months.

William A. Shea, senior partner and the man after whom New York's Shea stadium is named, said Mills will do "mainly tax work" but will also take on other topics "of his choosing."

Mills, who did not run for re-election in 1976, but resigned his post as Ways and Means chairman in early 1975 after a bout with alcoholism and his friendship with an Argentine stripper became public, said yesterday he expected to join the law firm around Oct. 1.

Reached in his home town of Kensett, Ark., where he was vacationing, Mills said he had been doing "just what I want to when I want to" since leaving Congress last year.

He said a "number of people thought I should be doing something" and they "talked me into" doing into law practice. Mills, who has continued to live in Crystal City since leaving Congress, said he would do no lobbying in his new job.

Shea has been one of the most powerful Democrats on the New York scene for more than two decades.

He was involved in the campaigns of both New York Mayor Abraham D. Beame and Governor Hugh L. Carey. He is a member of several corporate and bank boards and was a director of Security National Bank, whose officers were accused of making illegal political contributions.

His law firm is one of the most important in New York.

But New Yorkers know him best for his role as head of a committee that in 1962 brought the city its Mets baseball team and the new stadium that bear's his name.

One shareholder, who like many others in the room had watched his stock drop in price from a one-time high of $9 to just above $1 in the over-the-counter market today, asked Broyhill when American Realty would pay a divided again. Broyhill said that depends on how fast the firm can pay off its debt.