The Treasury Department has finished tallying its books for fiscal 1981, the fiscal year that just ended. The final totals are set forth in the Data Base above. If you check back to the government's initial estimates for fiscal 1981--as set forth in Jimmy Carter's budget message on Jan. 28, 1980--you'll find that the experts generally missed the boat.

The Office of Management and Budget estimated then that FY 1981 revenues would come to $600 billion--quite close to the actual figure, $602.6 billion.

But the original estimate called for spending of $615.8 billion, and a resulting deficit of $15.8 billion. The final report says the government actually spent $660.5 billion, and the deficit for the year was $57.9 billion.

The biggest mistake in the original estimates involved interest expenses. In the original budget message, Carter said the government would pay $67 billion in interest on the national debt during the year. In fact, interest payments came to $95.6 billion.

Carter, incidentally, revised his fiscal 1981 estimates two months after he delivered the budget message. In the revised estimate, made when federal deficits were becoming a hot campaign issue, Carter predicted FY 1981 revenues of $615 billion, spending of $613 billion, and a surplus of $2 billion.