When the matching process occurs, the fields with API like-like values on Payment Txns and contacts will update

• If the value has changed

Eg: Phone number on the  contact is 0411111111, but the new Payment Txn has 0422222222 in the Phone number field, the value will be updated to 0422222222.

The field value will not change

• If the value on the field on the Payment Txn and the Contact are the same
• If the field is blank

Eg: Phone number on the  contact is 0411111111, but the new Payment Txn has no value in the Phone number field, the value will be retained with 0411111111.

However, this behavior does not apply to Checkboxes. Checkboxes are always considered to have a value, either TRUE or FALSE.

Eg: If a Contact Record has a checkbox ticked to TRUE, and a new Payment Txn has the same field not checked FALSE, the field on the contact record will be updated to FALSE.

Please take this into consideration when creating your Payment Forms.