Entering an Invoice/Payment Wash
You can create an invoice at the time you enter a payment.
If operating on an accrual basis, you increase your revenue with the invoice, and you increase your cash with the payment. Because both are entered at the same time, they wash each other out. Washing an account only means bringing the accrual account to a zero balance.
In ACS, when you select the Invoice/Payment Wash option, an invoice is automatically generated at the time you post the payment, so a wash occurs.