I donated by check to a charity in mid-December. They have not yet cashed my check. If they don't do so by the time I file can I still deduct this?

[ChristinaS]

Yes. According to IRS guidance:

Checks. A check you mail to a charity is considered delivered on the date you mail it. Before deducting, however, I would verify with the charity that the check was received. You are not in the wrong for a deduction, but you also should ensure that the money is literally paid to the organization. If they lost the check, you haven't paid anything.

Page 13

https://www.irs.gov/pub/irs-pdf/p526.pdf

[gglater]

Your answer leaves my question unanswered.  If I sent my check and they have not cashed it (for whatever reason) can I deduct it?  If they lost it, isn't that their fault, not mine?  If I send them a replacement check can I use the date of the original check or do I lose the donation for last year?

[ChristinaS]

Yes, you can deduct it if its cashed. The check mailed date concept works on the assumption that the check in question is eventually cashed. You won't get a deduction in 2016 if the check needs to be replaced with a new one UNLESS YOU HAVE PROOF that you mailed the check (like Certified Mail).
The IRS does not offer explicit guidance on this issue. This is general practice.

[gglater]

Thank you!

[ChristinaS]

You're welcome!