1. Open the Accounts List window (Lists > Accounts) and click New. The Account information window appears. 
2. Select Bank from the Account Type list.
3. Enter an unused account number. 
4. Enter a name such as Contra Payment.
   
   
5. Click OK.

Record your sales and purchases as you usually do (including assigning the correct tax code). When you're ready to offset sales against your purchases, record a contra payment. It's a two-step process.

1. Record a payment for your sales.
   
   1. In the Receive Payments window, enter the Contra Payment account in the Deposit to Account field.
   2. In the Customer field, enter the customer’s name.
   3. Enter the amount that you need to offset against your outstanding invoices.
      
      
      
2. Record a payment for your purchases.
   
   1. In the Pay Bills window, enter the Contra Payment account in the Pay from Account field.
   2. In the Supplier field, enter the supplier’s card.
   3. Enter the amount that you need to offset against your outstanding purchases.
       

After these entries are made, your bank accounts will not have been affected; yet the receivable and payable accounts have been reduced. The Contra Payment account balance should be zero.