In theory, you could issue a receipt for each and every donation. However, providing a single receipt once a year is recommended. This single receipt serves as a centralized record of all the donor's contributions. This saves the donor time by eliminating the need to keep track of many single receipts. Donors can better manage their data and prepare for accounting and tax returns this way. It's always advisable to send year-end invoices to donations before January 31st of the following year. Finally, sending donation receipts is critical for completing legal requirements as well as maintaining a positive relationship with your donors.