Configuring and styling the information displayed
You can configure the styling and which columns are displayed in the letter by going to Administer > CiviContribute > EOY Payment Summary Tokens.
Understanding how the list of contributions is created:
The payment token used in the end-of-year letters will include all contributions where the status is set to 'completed' and the contribution's financial type is set to 'deductible'.
Edge cases:
1) If a contribution record has a non-deductible financial type but one of the line items in that contribution record has a deductible financial type, that line item only will be included in the list of donations.
2) It could happen that a contribution record was created in 2025 but the payment was only added in 2026. In that case, it is important to remember that it is the contribution's date (2025) that determines if the payment gets added to the letter or not.
3) If the contribution record is set to 'partially paid', its payments are not included in the letter. If you often have partially paid contributions, you are better off using pledges to record pledges or invoices.
Large Batches Thank You Letters
If you are processing a large volume of thank you letters, you need to use the large batches feature from the actions dropdown instead of the regular thank you letter option to avoid extensive delays or even crashing the server.