By Adam Bernstein, Washington Post staff writer:

Edwin S. Cohen, 91, an eminent tax lawyer who became undersecretary of the Treasury in the first Nixon administration and composed tax-tinged doggerel, died Jan. 12 at his home in Charlottesville. He had heart disease.

In government service and private practice, Mr. Cohen had a major role in the formation of modern tax policy. He contributed heavily to the Internal Revenue Code of 1954, a massive overhaul of the federal income tax system.

A moderate Republican, Mr. Cohen was tapped in 1969 to serve as assistant secretary of the Treasury for tax policy and later was undersecretary before leaving in 1972. He had a strong role in passage of the Tax Reform Act of 1969, providing another round of sweeping changes to the tax code that affected individuals, corporations and foundations.

Among other things, the 1969 act provided the first provisions requiring foundations to give away annually a percentage of their assets. It also limited individuals from having to pay more than 50 percent of earned income in federal income taxes.

Mr. Cohen spent the rest of his career teaching at the University of Virginia, his law school alma mater, and serving of counsel to the law firm of Covington & Burling in Washington.

He also wrote a memoir, “A Lawyer’s Life: Deep in the Heart of Taxes” (1994), and verse about tax conundrums that he often used when lecturing.

Of the tax-law quirk known as the “marriage penalty,” which makes married couples owe more than singles, Mr. Cohen once wrote:

“When a boy meets a girl and they determine to wed,

They are not likely to think of the taxes ahead.

If one earns the wages and other’s keeping house,

On the 15th of April each is happy as a spouse.

But if both are earners and their income’s the same,

They’ll find it’s been costly to share the same name.”

Edwin Samuel Cohen was born Sept. 27, 1914, in Richmond, where his father ran the Cohen Bros. department store.

He was a 1933 Phi Beta Kappa graduate of the University of Richmond. After completing law school in 1936, he went to work for Sullivan & Cromwell, a prestigious New York law firm.

There, he helped craft the Investment Company Act of 1940, which regulates the mutual fund industry. Years later, he was external tax counsel to the Investment Company Institute, the national organization of mutual fund companies.

At Sullivan & Cromwell, he also worked for partner Norris Darrell, who served as president of the American Law Institute and headed a project that led to the creation of the Internal Revenue Code of 1954.

After starting his own New York firm in 1949, Mr. Cohen advised the House Ways and Means Committee on the tax code reform. U-Va. recruited him in 1965 from his firm — then known as Root, Barrett, Cohen, Knapp and Smith — to teach taxation law.

Mr. Cohen was amply involved in several federal and state tax advisory bodies and commissions. He was a recipient of the Alexander Hamilton Award, the Treasury Department’s highest honor, and the American Bar Association’s distinguished service award.

Once a member of the University of Richmond tennis team, he continued to play tennis until last year.

His first wife, Carlyn Ladenberg Cohen, whom he married in 1936, died in 1942.

Survivors include his wife of 61 years, Helen Herz Cohen of Charlottesville; a son from his first marriage, Edwin C. Cohen of New York; two children from his second marriage, Roger Cohen of Denmark, Maine, and Wendy S. Cohen of Charlottesville; and two grandsons.