You are correct that you are in a risk zone. When you make a donation of a single item or "group of similar items" over $5000, the IRS requires that you have a signed appraisal, and you get a financial official from the charity to sign a paper copy of form 8283 listing the donation (that you mail to the IRS after e-filing the rest of your return.). And this is required even if the "group of similar items" is split between several charities.
The problem is that the IRS offers no guidance as to what actually a "group of similar items" means, or what kinds of timing are allowed.
Let's say you donate the contents of your parent's house after they pass away. Is "furniture" a different group of similar items from "dishes and other kitchen goods" or is it all one group of "used household items"? I'm not aware of any specific guidance (publications or instructions) that the IRS gives to taxpayers. If you want to claim more than $5000 for donations of similar non-cash items, you may wish to consult your own professional for an expert opinion that covers your exact needs.
