What if we lose our determination letter from the IRS?

Summary:

There is a simple procedure for getting a replacement. (These letters are sometimes also called 'recognition' letters.)

Linda Arnsbarger wrote to CharityLaw (a service of CharityChannel -- http://www.charitychannel.com) on July 18, 2002:
Instead of getting the original letter, the organization can call the IRS
Cincinnati office toll-free at 877-829-5500 with its name and EIN, and the IRS will
check its database and prepare a new letter and fax it to the organization
on the same day, with hard copy to follow by mail.

Sandy Deja,
Author of "Prepare Your Own 501(c)(3) Application"
an ebook for lay people - http://www.501c3book.com/, replied to a similar question on May 14, 2004, with this suggestion:
The IRS does not "replace" determination letters. You can, however, ask for
a letter confirming that their records show that your organization is tax
exempt. Send your request, signed by a board member or officer, to:

Internal Revenue Service
Attn: Exempt Organizations
P. O. Box 192
Covington, Kentucky 41012-0192