In order to claim a tax deductible donation for a single item or “group of similar items“ of more than $5000, you must have a signed appraisal by a qualified appraiser, and you must mail the IRS a copy of form 8283 which is signed by both the appraiser and by a financially responsible official of the recipient organization.
The IRS is not specific on what a “group of similar items” means. However, if you were to try to group a large donation of used household items into smaller groups, such as “used furniture“, “used kitchen ware”, “used household accessories“, and so on, each less than $5000, but totaling more than $5000, that could certainly raise a red flag.
You can deduct out of pocket costs that you paid in connection with providing a service to a charity. If you donated the items to a charity, and you paid someone to pick them up from your house, and deliver them to the charity, then I think that would be separately deductible from the value of the items.
