Why didn’t the budget include tax rises to pay for the NHS funding boost?

In June the prime minister promised that NHS funding would increase by about £4bn in each of the next five financial years.1 Yet in the chancellor’s recent budget there was no increase in income tax, VAT, or national insurance to fund this.2

The Office for Budget Responsibility is admirably clear about where this extra money was found in the absence of tax rises: there were better than expected tax receipts.3 “The budget spends the fiscal windfall rather than saving it,” it …