Is this what the government will do?
No. It is a what-if: one pledge, paid for one way, on official figures. A real Budget pays for many things at once and the Office for Budget Responsibility checks the sums. Where a pledge said how it would be paid for, the page shows that too.
Why does a tax need only a fraction of a penny?
Because a penny on a big tax raises billions. HMRC's figure for 1p on the basic rate of income tax is several billion pounds a year, so a pledge costing a few hundred million needs a small fraction of that. Tax rates are usually set in whole pence; the fraction shows the scale.
Why does borrowing still show a range when the pledge is paid for in full?
The pledge's cost and the tax's yield are both estimates. If the pledge costs more than expected and the tax raises less, the gap is borrowed; the other way round, borrowing falls. The range shows both ends.
Which pledges are here?
Every promise card with a yearly cost to the public purse, from any party, in government or not, under the same rules. Pledges that raise money, such as a new tax, are not listed, because they need no paying for. They are on the promise ledger.
Does a tax rise or a cut change how the economy behaves?
HMRC's figures include how taxpayers respond, such as reporting less income, but not wider effects on prices, jobs or growth. Cuts are counted pound for pound. The sandbox on the home page shows rough effects on prices and growth, as wide ranges.
Who decides each of these?
Taxes, spending and borrowing are decided by the government and voted through by Parliament. The interest on borrowing depends on Bank Rate, which the Bank of England sets, and on the markets.