You can deduct your contributions only in the year you actually make them in cash or other property (or in a later carryover year, as explained later under Carryovers). This applies whether you use the cash or an accrual method of accounting.
If you use a pay-by-phone account, the date you make a contribution is the date the financial institution pays the amount. This date should be shown on the statement the financial institution sends to you.
A gift to a charity of a properly endorsed stock certificate is completed on the date of mailing or other delivery to the charity or to the charity's agent. However, if you give a stock certificate to your agent or to the issuing corporation for transfer to the name of the charity, your gift is not completed until the date the stock is transferred on the books of the corporation.