The federal government's budget deficit fell sharply in the fiscal year ended last month,to $148 billion, as receipts rose a strong 11.1 percent and spending went up only 1.2 percent, administration officials reported yesterday.

Spending increased from $990.2 billion in fiscal 1986 to $1,002.1 billion, primarily as a result of an $11.7 billion increase in Social Security payments and an $8.4 billion rise in military outlays. The largest decline, $9.1 billion, came in agriculture, partly as the result of the sale of loans, the proceeds of which were counted as a cut in spending.

Individual income tax payments, boosted by a significant increase in capital gains taxes, rose 12.5 percent, to $392.6 billion. Corporate income tax payments jumped 32.9 percent, to $83.9 billion, following a large rise in corporate profits and an increase in corporate income taxes in last year's tax bill.

Social insurance taxes, such as those for Social Security, rose 6.8 percent, to $303.3 billion. Excise taxes, estate and gift taxes and customs duties also increased significantly.

President Reagan had disclosed the $148 billion deficit figure in a press conference last Thursday. The other details were announced jointly yesterday by the Treasury Department and the Office of Management and Budget.

The final figure was down $73.1 billion from the fiscal 1986 deficit of $221.1 billion. It was also down about $25 billion from the administration's estimate of January and about $10 billion lower than was estimated in August.

The difference between the actual 1987 deficit and the January estimates was due about equally to spending and receipts, with the former $13.5 billion below the January figure and the latter $11.7 billion higher.

As a result of asset sales and other actions to cut spending, outlays also fell at the Education, Energy, Labor, State, Transportation and Treasury departments and at some smaller agencies.

As measured by function, spending fell for international affairs; energy; natural resources and environment; agriculture; transportation; community and regional development; education, training, employment and social services, and general government. It also fell for general-purpose fiscal assistance -- revenue sharing -- which was eliminated.