Thanks
Assuming you owned these books more than a year, your donation
is the fair market value of the books. Use schedule A.
If the FMV is more than $500 you will also file form 8283.
Also file Form 8283 if the FMV is less than 500 but the total
of noncash gifts is over 500.
If the FMV is more than $5,000 you will also have to have
an appraisal and the apapraiser would sign the form 8283,
and you would have to file form 8453 if e-filing.
If the value is over 250 you will need a written receipt from
the recipient organization which includes the full description
of the gift. "One box of books" is not likely to work here.
And if this is appreciated property, if the value exceeds
30% of Adjusted Gross Income, the excess will have to be
carried to next year.