GiveCalc UK: Calculate your Gift Aid tax relief

We're launching GiveCalc for UK taxpayers, a free calculator that shows how Gift Aid affects your taxes. Enter your income and donation amount, and GiveCalc computes your tax relief — helping you understand the true cost of giving.

Gift Aid is the UK's primary tax relief for charitable giving. When you donate to a registered charity, the tax system provides relief at two levels:

1. Charity reclaim: The charity claims back the basic rate tax (20%) on your donation. For every £1 you give, the charity receives £1.25 from HMRC.

2. Donor relief: If you pay tax above the basic rate (40% higher rate or 45% additional rate), you can claim back the difference on your Self Assessment.

A higher rate taxpayer donating £1,000:

Component	Amount
Your donation	£1,000
Charity receives (grossed up)	£1,250
Your tax relief (40% - 20% on £1,250)	£250
Net cost to you	£750

The charity gets 25% more than you gave, and you save 25% on your donation — everyone benefits except HMRC.

GiveCalc computes your Gift Aid tax relief based on your specific circumstances:

• Employment and self-employment income
• Region (including Scottish income tax rates)
• Family situation (marriage, children)

The calculator shows:

1. Tax savings: Your total reduction in income tax liability
2. Marginal savings rate: Tax saved per additional pound donated
3. Net cost: Your actual out-of-pocket cost after tax relief

GiveCalc UK showing a higher rate taxpayer donating £1,000

Scotland sets its own income tax rates, which differ from the rest of the UK:

Band	Scotland	Rest of UK
Starter (19%)	£12,571–£14,876	—
Basic (20%)	£14,877–£26,561	£12,571–£50,270
Intermediate (21%)	£26,562–£43,662	—
Higher (42%)	£43,663–£75,000	—
Advanced (45%)	£75,001–£125,140	—
Top (48%)	Over £125,140	—

GiveCalc automatically applies the correct rates based on your selected region.

For high earners (income over £100,000), Gift Aid donations can restore some of your Personal Allowance. The Personal Allowance reduces by £1 for every £2 of income above £100,000 until it reaches zero at £125,140.

Gift Aid donations reduce your "adjusted net income" for this calculation, potentially restoring your Personal Allowance and creating an effective marginal relief rate of up to 60% (or 63% in Scotland).

Visit givecalc.org and select "United Kingdom" to calculate your Gift Aid tax relief. The calculator uses PolicyEngine's validated UK tax model to compute accurate results for your specific situation.

The source code is open source, and we welcome contributions and feedback.