As long as you haven't filed yet or your return has been rejected you can add your charitable donations by taking the following steps.
- Sign into TurboTax Online
- Click Taxes > Tax Timeline > Take me to my return (if you already filed this will not be an option)
- Click on the Federal Taxes tab > Deductions & Credits sub-tab
- Scroll down until you see Charitable Donations and click Show More
- Click Start/Revisit next to Donations to Charity in 2016
- Proceed through the interview to entry in your church donation
If you have filed and your return has been accepted you will need to amend your tax return if you have enough deductions to itemized your return. If not you do not need to amend as adding the donations will not make a difference.
Please see the following TurboTax FAQ for amend instructions.