You'll want to be aware of How Agencies Differ from Version 9 to v10 and consider Your Conversion Strategy.

Which is Your Situation?

There are two types of situations you may encounter.

• The Agency Payment Posting screen shows an outstanding balance from long ago, but the balance due IS CORRECT. The agency currently owes that amount for that family. See article: Agency - Old Item Due
   
• The Agency Payment Posting screen shows an outstanding balance from long ago, but the balance is INCORRECT (it  should be ZERO) because that agency no longer owes anything for that family. See article: Agency - System Entry

A negative agency payment may be posted to reverse a mistake. For example a payment may have been posted to the wrong family, or for the wrong amount.

The basic steps are to:

1. Go to the Agency Payment Posting screen. Choose to "include previously balanced charges" and click View Current.
2. Enter a negative payment (in the Payment column) to reverse the original entry or entries. Also enter a negative figure in the Amount box at the top. Post & Exit.

   Hint: You may also want to use the same Post Date that was used on the original entry and a comment like "Correction for voucher #1234".

3. Go back to View Current and enter the payment correctly. Again, you may want to use the same Post Date that was used on the original entry. 
4. Both items (the negative enry and the reposting) will appear in the current Deposit Report.
    
   1. If the items were for the same amount (like -100.00 and 100.00) they will offset each other and can be closed together in a new deposit report for a total amount of zero. In this case there is no effect on the amount originally deposited.
       
   2. If the items were for different amounts (like -75.00 and 100.00) this would affect the original deposit. In that case re-open the original Deposit Report and add the new items to it (use the Show All button to make these items available). Change the total amount of the depost and re-close.  

See the full article on Correcting an Agency Payment for more detail.

You may correct an agency adjustment by making additional adjustments. For example you may make two adjustments, one to reverse the original entry and another to correct it. This may be appropriate if an item had been posted to the wrong family, or for the wrong amount, or using the wrong adjustment code.

The basic steps are to:

1. Go to the Agency Payment Posting screen. Choose to "include previously balanced charges" and click View Current.
2. Enter a negative adjustment to reverse the original entry using the same Adjust Code that was originally used then Post & Exit.

   Hint: You may also want to use the same Post Date that was used on the original entry and a comment like "Correction for voucher #1234".

3. Go back to View Current and enter the adjustment correctly. Again, you may want to use the same Post Date that was used on the original entry.

See the full article on Correcting an Agency Adjustment for more detail.