Helping a charity? Don't forget to write off small expenditures plus mileage on your car. By Kevin McCormally, Chief Content Officer February 2, 2017 You’re less likely to forget the big check you wrote to a charity when tax time rolls around. You probably received a receipt from the lucky organization acknowledging your donation. If not, there should be a cancelled check or credit card statement floating around to serve as a reminder.See Also: 16 Reasons the IRS Will Audit Your Tax Return But it’s easy to overlook small out-of-pocket costs incurred while doing work for a charity. For example, ingredients for casseroles you prepare for a nonprofit's soup kitchen and stamps you buy for a school's fund-raiser count as charitable contributions. Save your receipts. If your contribution totals more than $250, you'll also need an acknowledgement from the charity documenting the support you provided. If you drove your car for charity in 2016, remember to deduct 14 cents per mile, plus parking and tolls paid, on your tax return. See IRS Publication 526 for more on charitable contributions. Plus, learn more about all 23 commonly overlooked tax deductions before you file your federal return.