Customer overpayments: reconcile, refund or keep a credit

A customer pays an invoice, then their accounts team pays it again. The extra deposit increases cash, but it doesn't mean you sold the same work twice. Keep the original invoice and deal with the excess through the customer's account.

This guide concerns a genuine overpayment. A cancelled order, returned goods or a price reduction changes the underlying sale and may need a different credit-note and tax treatment.

Confirm the payment trail before promising a refund

Compare the invoice amount with posted bank receipts, payment references and the customer's remittance. Make sure the supposed second payment isn't a duplicate imported line, pending authorisation or reversal. The duplicate feed guide helps identify that distinction.

Contact the customer through established details. Confirm which invoice the payment belongs to and how they want the excess handled. Don't send a refund to unrelated bank details just because an unexpected email requests it. Follow the original payment provider's refund process where relevant.

Keep the invoice and excess separate

This fictional invoice INV-204 is $660 and has already been recorded as a sale. The customer sends two separate $660 bank payments. No work was cancelled and no price changed.

Event	Cash received so far	Invoice still owing	Customer credit
Invoice issued: $660	$0	$660	$0
First payment: $660	$660	$0	$0
Second payment: $660	$1,320	$0	$660

Refund route

Return $660 using the confirmed payment route. Match it to the overpayment.
Net cash retained: $660.
Customer credit remaining: $0.

Agreed credit route

Customer agrees to retain $660. Later invoice INV-219 is $880; apply the credit and collect $220.
Total invoices: $1,540.
Total cash retained: $1,540.
Customer credit remaining: $0.

Original ASBG ledger and settlement diagram. Until the customer gives an instruction, the $660 remains an unresolved amount owed to them.

MYOB's customer overpayment instructions distinguish overpayments and double payments and allow the resulting credit to be refunded or applied to invoices. Use the product's overpayment workflow. Don't create a negative sale from scratch merely to make a bank line match when the original sale hasn't changed.

If the excess is only part of a payment

For a $660 invoice paid with $700, apply $660 to the invoice and track the $40 excess. The payment record must still account for the full $700. If $25 is refunded and the customer agrees to retain $15, document both decisions and leave exactly $15 on the account.

Do not automatically write small credits off as income. If the customer cannot be contacted, retain the liability and obtain advice about the applicable unclaimed-money and record obligations. The passage of time alone doesn't establish that the money is yours.

Refund through the correct payment channel

For direct bank payments, confirm the recipient and references through your normal customer-verification process. For card or platform payments, use the provider's permitted refund controls and keep its settlement report.

For example, MYOB's online-payment refund guidance requires refunds to the original card under its service terms. Other providers have their own rules. A bookkeeping refund entry doesn't necessarily send money, and a provider refund doesn't always arrive in the bank as a separate line.

Check tax treatment and the final account

Keep the original tax invoice and evidence of both receipts. Ask your registered BAS or tax agent to review any goods and services tax (GST) treatment if the software has reported the excess as another sale, or if an agreed credit later becomes payment for a new supply. Don't assume every kind of customer credit has the same tax effect.

After settlement, compare cash movements, the original invoice, the overpayment record and any later invoice. Send the customer a clear confirmation of what was refunded or retained. Include remaining credits in the monthly bookkeeping routine.

Key takeaways

• Record all real cash received without duplicating the sale.
• Get and keep the customer's refund or credit instruction.
• Confirm the credit balance reaches the documented amount after settlement.

Where to get help

Use your software's overpayment workflow and the payment provider's refund instructions. Ask your registered agent about tax corrections or unresolved old balances. Find related tasks in bookkeeping and BAS.