There is no maximum amount that you can donate. There is a maximum amount that you can deduct per year (it's 60% of your adjusted gross income) and there is a requirement that you document all of your donations thoroughly.
If you donate more than the limit for one year the donation deduction is carried over to the next year. If the amount of your donation is over $500 for non-cash items you will have to enter a lot of information about each of the charities that you donated items to.
You need to value all of your items in order to document your deduction and make sure that the value of items that you donated is not seen as too high by the IRS. There are a number of valuation guides out there to help with this (this one is from Goodwill). It is also a good idea to take photos of everything that you donate and make a thorough list.
@jdavisrn
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