GiveCalc

GiveCalc estimates what a cash gift to charity costs you after tax. It runs PolicyEngine's model of your household twice, without the gift and with it, and reports how much the gift lowers your net taxes: your taxes minus any benefits you receive.

In the US, GiveCalc counts federal and state taxes, and the local income taxes PolicyEngine models, such as New York City's. In the UK, it applies Gift Aid to your income tax. The charts show how your net taxes change with gifts from nothing up to your income.

In the US, a gift lowers your federal income tax only through the part you can deduct. If you take the standard deduction, you can deduct up to $1,000 of cash gifts from 2026, or $2,000 on a joint return; in 2025 you could deduct nothing. Above that, a larger gift lowers your federal income tax only once itemizing, gift included, would lower it more than the standard deduction does. Some states, such as California, let you itemize on the state return either way, so a larger gift can still lower your state tax.

A single 30-year-old in California earning $75,000 saves $220 by giving $1,000 in 2026, and the same $220 by giving $5,000. In 2025, the $1,000 gift saved nothing. Open the California example

In the UK, a basic-rate taxpayer saves nothing: Gift Aid's basic-rate relief goes to the charity.

Three federal rules took effect in 2026, and GiveCalc applies all three.

• Filers who take the standard deduction can deduct up to $1,000 of cash gifts, or $2,000 on a joint return.
• Itemizers deduct only the part of their gifts above 0.5% of their adjusted gross income.
• Filers whose income before itemized deductions reaches the top 37% bracket give up 2/37 of their itemized deductions, up to 2/37 of their income in that bracket.

Take a single 30-year-old earning $1,000,000 in Texas, which has no state income tax. Giving $110,000 in 2026 saves $3,500 more than giving $100,000: 35 cents for each extra dollar. Open the Texas example

In the US calculator, choose “Share of income” in the first step and enter a percentage, such as 10%. GiveCalc then works out the gift from the income you enter in step 3: everyone's wages, tips, self-employment income, interest, dividends and capital gains, minus any losses. The UK calculator asks for an amount.

After a US result, GiveCalc checks whether giving two years' gifts at once would save more tax. It compares giving your gift in the year you chose and again the next year with giving twice the gift in the first year and nothing in the second. It keeps your household and income the same in the second year, with everyone a year older, and applies that year's tax rules.

Bunching can lower your taxes when you itemize in the year you give and take the standard deduction in the year you skip. Take a single 30-year-old earning $150,000 who lives in New York, outside New York City. Giving $30,000 in 2026 and nothing in 2027 saves $2,820 more in tax than giving $15,000 in each year. Open the New York example

For a gift in the latest year GiveCalc offers, pick an earlier year to run the check.

With Gift Aid, a charity claims the basic-rate tax on your gift: 25p for every £1, so a £1,000 gift gives the charity £1,250. Taxpayers above the basic rate also save income tax: the difference between their rate and the basic rate, on as much of that £1,250 as they pay their higher rate on. GiveCalc shows that saving as your tax relief.

A donor in England, Wales or Northern Ireland earning £70,000 who gives £1,000 in 2026/27 saves £250. One earning £35,000 saves nothing, because the basic-rate relief goes to the charity.

GiveCalc uses Scottish rates for donors in Scotland, where relief starts at the 21% intermediate rate. Gift Aid also lowers the income that tapers the personal allowance above £100,000 and sets the High Income Child Benefit Charge, and GiveCalc counts both effects.

GiveCalc models cash gifts and assumes each one qualifies for the relief it applies. It leaves out:

• gifts of shares, property and goods;
• state tax credits that depend on which charity you give to, such as Arizona's and Mississippi's;
• countries other than the US and the UK.

GiveCalc treats each US gift as cash to a public charity. Gifts to donor-advised funds can't use the deduction for filers who don't itemize, and GiveCalc doesn't tell them apart. Use its estimates to plan, and ask a tax professional about your own return.

GiveCalc asks for no name, email address or account. To calculate, your browser sends the household you enter to GiveCalc's server, which runs the model and sends back the result. GiveCalc's code saves none of it to a database or file. The server's log records each request's type, such as a savings calculation, whether it worked and how long it took, without the household.

Each server keeps recent households and their results in memory to answer repeat questions faster, and drops them when it needs the room or shuts down.

When a link can reproduce a US calculation, GiveCalc puts your inputs in the page's address so you can share it. Your browser's history keeps that address, and opening it sends the inputs to the site's host, as any web address does.

GiveCalc runs PolicyEngine's open-source models of taxes and benefits, policyengine-us (opens in a new tab) and policyengine-uk (opens in a new tab). PolicyEngine is a nonprofit that provides free, open source software to compute the impact of public policy. It publishes the code for GiveCalc (opens in a new tab) and both models on GitHub.