Economists have said taxes will have to go up in the autumn Budget if the chancellor is to meet her self-imposed rules on borrowing to fund public services.
In her Labour conference speech on Monday, Reeves said the government was facing difficult choices and promised she would not take risks with the public finances.
The chancellor pledged to keep “taxes, inflation and interest rates as low as possible”.
But hinting at further tax rises, she said the government’s choices had been made “harder” by international events and the “long-term damage” done to the economy.
In its election manifesto, Labour said it would not increase National Insurance, the basic, higher, or additional rates of income tax, or VAT.
In an interview ahead of her conference speech, Reeves was asked if VAT could rise and she said: “The manifesto commitments stand.”
That form of words has been echoed by senior ministers at Labour’s conference, including Prime Minister Sir Keir Starmer.
But when pressed over whether she would have to put up taxes, Reeves said “the world has changed” in the last year – pointing to wars in Europe and the Middle East, US tariffs and the global cost of borrowing.
“We’re not immune to any of those things,” she added.