Other Budget measures, including a big boost to spending on public services, and other tax rises, are expected to raise inflation in the short term, which could prevent interest rates falling more quickly.
That will also have a knock-on effect on people’s spending power.
The government has pledged to make economic growth its priority and said people would have more “pounds in their pockets” by the end of the parliament.
In its general election manifesto, Labour promised not to increase taxes on “working people” – explicitly ruling out a rise in VAT, National Insurance or income tax.
The pledge has come under scrutiny, with some claiming that Labour have broken it with the rise in employer’s National Insurance Contributions (NICs), something the government has denied.
Reeves acknowledged on Thursday that the rise in NICs would affect pay.
“It will mean that businesses will have to absorb some of this through profits and it is likely to mean that wage increases might be slightly less than they otherwise would have been,” she told the BBC.
The Budget has sparked a debate over how much of the tax rise firms can absorb.
The Office for Budget Responsibility (OBR) forecasts that by 2026-27, some 76% of the total cost of the NICs increase will be passed on through a squeeze on pay rises and increased prices.
The OBR expects that as a result of the Budget, average household income – which includes the impact of tax changes directly and indirectly, and benefits – will increase only slowly over the parliament.