here is an article about museum membership and tax laws
http://www.aam-us.org/pubs/mn/MN_ND03_LawEthics.cfm
 
found by a Bing search using the terms
museum membership percentage tax deduction
 
other hits might help too.
 
Barbara Hass, retired librarian
 
In a message dated 10/14/2010 3:58:16 P.M. Mountain Daylight Time, [log in to unmask] writes:
Hello,

We wondering if anyone had a standard formula for calculating the percentage of a museum membership that is tax deductible. Like most museums, we offer benefits to people who join and have pegged the number of benefits to the level of membership. Do any of you who work in development or membership have a formula that you use to determine the value of those benefits received?  We are concerned that if we estimate a high value to member benefits then the amount of the membership that is tax-deductible becomes very low. As a result, membership in the museum would not be very attractive.

Thank you,

Deborah O'Neill
Director of Education
Mount Vernon Hotel Museum & Garden
421 East 61st Street
New York, NY  10065
(212) 838-6878
www.mvhm.org


========================================================= Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).

========================================================= Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).