Sunak announced plans to increase the National Insurance threshold by £3,000, up from a previous pledge of £300.
This means it will be equivalent to the income tax threshold and will give 70% of workers an effective tax cut.
Sunak said the National Insurance changes will offer a £6bn tax cut for 13 million people, amounting to an average cut of £330 a year.
Sunak described the NI threshold increase as "the single biggest tax cut for a decade". However, Torsten Bell, head of the Resolution Foundation thinktank, said: "This is a tax cut for the middle and top of the income distribution - only £1 in £3 of the benefit goes to the bottom half."
In addition, Sunak pledged to cut the basic rate of income tax by 1p in the pound by the end of Parliament in 2024.
Sunak says income tax has only been cut twice in 20 years, adding that "that shows how hard it is to do".
Sunak says before the end of this parliament, in 2024, the basic rate of income tax will be cut from 20p to 19p in the pound.
To coincide with the Spring Statement the OBR has also released its latest growth forecasts, slashing UK GDP growth from 6% to 3.8% this year due to "unusually high uncertainty".
Growth then falls to 1.8% in 2023 before picking up to 2.1% in 2024, 1.8% in 2025 and 1.7% in 2026.
The OBR's forecasts also show that inlation will now average 7.4% this year, after this morning's ONS data revealed that CPI inflation rose to 6.2% in February.
John Phillips, national operations director at Just Mortgages, said: “As expected, there wasn’t anything directly related to the mortgage sector in the Spring Statement.
“The housing market has shown its resilience recently, and although the stamp duty holiday certainly kick-started a frenzy in the last few years, another SDLT break isn’t necessary to keep the market moving.
“It is encouraging that measures have been put in place to ease the cost-of-living crisis, and although the inflation and rising energy prices may impact some, there are still people looking to move to keep the market buoyant and brokers busy.
“As activity settles back to pre-pandemic levels, there is still a steady stream of buyers, and with the Monetary Policy Committee increasing base rate recently, advice from brokers will be even more critical than usual. Rates look set to continue rising and this may spark moves and remortgages as borrowers and brokers look to fix ahead of rates hitting their peak.”
