Big banks just received the first installment of benefits corporate America will reap from the new federal tax law. The haul: more than $2.5 billion.

The latest gain came Tuesday when Goldman Sachs Group Inc. reported first-quarter profit that rose 26% from a year earlier. This was aided by a lower corporate tax rate that boosted earnings by about $232 million.

Overall, the combined earnings of Goldman and the four major national banks— JPMorgan Chase & Co., Wells Fargo & Co., Citigroup Inc. and Bank of America Corp. —increased by more than $2.5 billion in the quarter because of the lower corporate rates under the tax-overhaul law enacted in December, according to an analysis of the banks’ results by The Wall Street Journal.

That amount is only a modest-size chunk of the banks’ total first-quarter earnings—less than 10% of their combined net income applicable to common shareholders. But it comprises a major chunk of their year-over-year earnings growth.

Without the tax savings resulting from the new lower corporate tax rate, Wells Fargo’s earnings would have declined from a year ago instead of increasing, and much of the year-over-year growth at Citigroup and Bank of America would be gone. Losing the tax bump would have cut the earnings growth of JPMorgan to 28% from 35%; for Goldman, growth would have shrunk by at least a quarter.