Here is some guidance. The IRS defines fair market value as the amount a willing buyer would pay a willing seller. The feelings of the donor as well as federal regulations must be considered when determining the use of a donation. Volunteers for charitable organizations can deduct unreimbursed expenses.
Deductions only reduce tax liability on income that has actually been received.
Depending on the position of the corporate donor, contributions used for activities outside the US may or may not generate a tax benefit for the corporation. A deduction cannot be taken when no income has been earned. By David Keene, CPA, and David Endicott. But some operate in ways that risk damage to organizations' reputations and penalties for taxpayers. Two articles discuss the problems.