While Congress and the Bush administration battle over the size of next year's budget deficit, the deficit for this fiscal year continues to mount higher and higher.

Fueled by disappointing tax receipts and cash outlays for the savings and loan cleanup, the deficit for May alone ballooned to $42.5 billion, according to Treasury data released yesterday.

With another four months to go, the fiscal 1990 budget gap has nearly matched the total for all of 1989.

This year's deficit numbers also burst through the limits set for 1990 under the Gramm-Rudman-Hollings deficit reduction law. According to the law, which the 1990 budget was designed to meet, the deficit was not to exceed $100 billion.

But in the fiscal year that started last Oct. 1, the federal government has run up a deficit of $151.7 billion, up from $113.2 billion in the same period of fiscal 1989.

Analysts estimate that the 1990 budget deficit will climb to about $200 billion.

The May deficit more than wiped out April's encouraging $41.8 billion surplus from income tax payments.

The deficit also slightly exceeded the consensus of economic forecasters surveyed by Dow Jones Capital Markets Report. That consensus forecast was $39.8 billion. The small difference meant the new figures would have little impact on the markets.

The government's monthly deficits fluctuate depending on the cycle of tax payments. But last month's deficit also exceeded the May 1989 deficit by $17.2 billion.

About $7.3 billion of that increase was caused by spending on the bailout of troubled savings and loan institutions, Treasury data showed.

Much of the rest was caused by lower-than-expected tax receipts. Despite continuing growth in the economy, corporate and personal income levels have lagged behind forecasts used in budget planning.

Higher-than-expected interest rates also have raised the cost of government borrowings.