IRS publication 560 can help you do it, but the documentation is extensive.

IRS publications provide little guidance on this topic, if it has been acted on at all.

IRS publications 54, 514 (are there any corporate ones?)

IRS publications are available for sale from the Government Printing Office.

For donations of more than $500: Check IRS Publication 526 to see what additional records you should have.

For more information on exemptions, dependents and whether you or your dependent needs to file a tax return, see IRS Publication 501.

A step-by-step worksheet for this calculation can be found in IRS Publication 560.

The following example is extracted from IRS Publication 946:

IRS Publication 560 refers to them as "Qualified Plans."

If you choose to defer interest reporting, you may want to refer to IRS Publication 550 for full instructions and information.