In the US taxpayers track their charitable giving and use it to reduce their taxable income at filing time.

In the UK when you donate to a charity you attest to that charity that you are a UK taxpayer and that the donation is therefore gift aid eligible, and the charity just goes to the tax office and collects an extra 25% on top of the donation.

So in the US, say, you earn $150, pay $50 in tax withholding, then donate $100 to a charity, then claim the donation to the IRS to say you shouldn’t be taxed on $100 of your earnings, so you should only have paid $30 in taxes, and you claim back $20. You have $20, charity has $100, taxman has $30.

In the UK you earn £150, pay £50 in PAYE, then give £80 to a charity, keeping £20 and telling the charity they can giftaid it. Charity goes to the taxman and asks for another £20. End result, you have £20, charity has £100, taxman has £30.

Essentially the same outcome - charity donations are tax advantaged - but the paperwork for taxpayers is much simpler.