Former Central Intelligence Agency officer Frank W. Snepp III said yesterday he owes the Treasury $37,402.75 in profits from his unauthorized book on the fall of Saigon, according to an accounting filed in U.S. District Court in Alexandria.

The accounting was ordered by U.S. District Court Judge Oren R. Lewis. The judge, after a two-day hearing in June, had concluded that Snepp, by publishing his book, "Decent Interval," "willfully, deliberately an surreptitiously" breached the secrecy agreement he signed when he joined the CIA in 1968.

Justice Department lawyers had estimated that Snepp made about $60,000 from the book and that's what he should pay the government. But Snepp's accounting states that he received gross revenues of $61,590 from the book minus expenses and taxes of $24,187.25.

Snepp's attorney, John Sims, said a $175,000 bond, covering all the money Snepp would be expected to pay during his appeal, was posted yesterday and probably nothing will be paid until the appeals are exhausted.

A Justice Department lawyer said yesterday that Snepp's accounting is a minor detail and probably won't be challenged until the appeals are finished.

According to his accounting, Snepp was paid $10,500 as an advance on signing the book contract, $11,090 as an advance on submitting his manuscript, $20,250 as an advance on the sale of paperback rigts and $19,750 as the balance owed him by Random House publishers for 1978 royalties.

Under the terms of his contract, Snepp said in court papers, he is limited to receiving a maximum of $40,000 a year for the book.