Can I enter 2016 donations in It's Deductible?

[mesquitebean]

Yes, if you are referring to the ItsDeductible website.  But the donation values may or may not be as accurate anymore.   I don't know how it handles the values for old years.

Why are you doing this?  Are you planning to prepare a 2016 return?

If you plan to import them into a 2016 return you are preparing, I don't know if the imported values will be for what they were in 2016 or whether they will update.  I don't know if they will be the original 2016 values or not after they are imported.   Normally values can change when imported since values are updated at the end of a year.  But I don't know whether the updates are retroactive at that website or not, or whether each year's values are frozen.

So this answer is only telling you how to do it.  

The ItsDeductible screen normally has a HOME tab and tabs for 3 years.  See the screen image below on how to go to the HOME tab and designate one of the tabs to be for an older year.