When entering a gift, the tax-deductible amount defaults to the same amount as the gift. However, the tax-deductible amount may be different if goods or services were received in exchange for the gift. At the writing of this explanation, the IRS rules currently require notification to a donor (constituent) when they receive a good or services in exchange for a single payment in excess of $75. For example, if a constituent purchases a ticket to a gala for $200 but will receive a meal that costs $50, only $150 is considered tax-deductible because the constituent received something in exchange for the gift.
Be sure to check with current local, state, and federal regulations and your accountant regarding tax-deductible giving to ensure you are in compliance.