When a donor contributes $75 or more and receives something of value in return, this is called a "quid pro quo" gift (which essentially means the donor received something in return for the donation).  When charitable nonprofits thank donors for quid pro quo gifts they must follow the IRS requirements in their ‘thank you’ letter.

What is required to acknowledge quid pro quo gifts?

When a donor gives a contribution in excess of $75 and also receives something of value from the nonprofit in return (there is an exception for "token" gifts) the nonprofit is required to provide the donor with an explanation of the fair market value received in return for the donation.

• Read about quid pro quo gift acknowledgments from the IRS website.
• Rules about quid prop quo gift acknowledgments are on page 10-11 of IRS Publication 1771.

Read more about saying ‘thank you’ to donors.