Even for the world’s largest asset manager, every million counts.

Among the thousands of provisions up for inclusion in the budget deal being crafted this weekend by the Legislature and Gov. Andrew M. Cuomo are a few dozen words that could save BlackRock, the New York-based financial firm, millions of dollars in city taxes in the future.

The provision was proposed by Senate Republicans last week as an amendment to an otherwise routine extension of state tax law. It would allow BlackRock, which earned a record profit of more than $2 billion last year, to be taxed by the state as a general business corporation rather than as a bank, saving it at least $3.5 million — and possibly several times that much — in city taxes each year.

A spokeswoman for BlackRock declined to comment. Scott Reif, a spokesman for the Senate Republicans, said the amendment was intended to correct a running flaw in the state’s tax code that for years has effectively stranded BlackRock, one of the world’s largest financial companies, in the wrong section of the code.

“Our budget proposes a technical fix that will allow companies to avoid the unintended negative consequences of an otherwise good and necessary provision,” Mr. Reif said. Aides to Mr. Cuomo and the Assembly speaker, Sheldon Silver, said the matter was still under negotiation. It is unclear how many other companies it could affect, and thus how much tax revenue might be gained or lost as a result of the change.