Some companies will have to move operations to the EU due to trade barriers, Office for Budget Responsibility says.
Income tax thresholds will also be frozen, instead of allowing people to take home more of their pay as had been planned.
A number of changes are coming, including 5% mortgages and a longer stamp duty holiday.
Following PMQs, the chancellor Rishi Sunak gives his budget for 2021 which will lay out support for the economy and people following the year's pandemic and lockdown effects. The chancellor is expected to extend furlough schemes and support for businesses but questions remain about how the country will pay for the support packages rolled out during 2020.