At times, there is a need to refund an EFT for a customer that was processed. At this time, when necessary, a refund is done in your Authorize.net account. Please use this guide to see how this action is performed. https://tan-link.zendesk.com/hc/en-us/articles/360030281091-How-to-refund-or-void-a-payment-through-Authorize-net-and-adjust-in-reports When done, to ensure that your books balance, the refund must be removed from your Tan-Link site also.
To do so you will go to CUSTOMERS > Edit Draft Transactions
A window as seen below will come up. Search for the Account ID the refund was issued on. In the Approved column change the "1" to zero. This will mark the payment as Declined in the Customer's Account without adding a past due.