510 - Future date. Usage: At least one other status code is required to identify the data element in error.

The insurance company is rejecting this because a payment/adjustment that you entered in to Therabill was entered with a post date in the future.

When sending a secondary claim (electronically), the adjudication information (all the payments and adjustments) from primary is sent on the electronic claim in a section called Coordination of Benefits (COB).   The post date of the payment/adjustment is part of this Coordination of Benefits information.

How to Fix

You have a couple of options here.

1. Edit the payment that you have applied to this session to set the post date in the past.   Once you have updated the post date, go ahead and resubmit the claim.
2. Wait to submit the claim until after the post date of the payment.