I've been refunded money for an expense - the full amount - how do I categorize it?

@max-rather-good- 

Assign the same expense category to the deposit that you assigned to the check/bill/expense.  That will reduce the expense.

Let me guide you on who to record a refund and categorize them in QuickBooks Online (QBO), max-rather-good-.

Refunds are recorded differently depending on how the purchase is recorded. If you enter expenses or write checks, you can follow the steps below: 

1. Click the + New Plus and then Bank Deposit.
2. Go to the Add funds to this deposit section:
   • Enter the amount refunded by the vendor and choose the Category/Account that you selected on the initial expense or check.
   • If this refund was for an expense that you linked to a customer or project, select the Track returns for customer checkbox, then select the customer or project. That way, your costs will not be overstated.
3. If you deposited customer payments for invoices into the bank account along with the vendor refund, add them in the Select the payments included in this deposit section.
4. Once done, press Save and close.

For other options on how to record a refund or credit from a vendor, you can check out this article: Enter vendor credits and refunds in QuickBooks Online.

If you are trying to refund a customer, you can use Refund receipts. We can use this method if the customer is asking for a refund for an item or service. Let's ensure we didn't enter a credit note yet to avoid a double refund. To do this, here's how:

1. Click the New Plus button.
2. Choose Refund receipt or Give refund.
3. Select the Customer dropdown, then choose the client you want to refund.
4. Choose the bank you deposited the payment for the invoice to in the Refund From dropdown.
5. Add all products or services the customer returned in the PRODUCT/SERVICE column.
6. Make sure to fill in the service date, quantity, rate, amount, tax, and other fields accordingly, then select Save and close. 

When you refund a customer's overpayment or credit, record it using a Check or Expense. For the step-by-step guide, you can refer to this article: Record a customer refund in QuickBooks Online.

Also, categorizing your transactions ensures they match your real-life bank statements. It's important to reconcile them every month to monitor the growth of your business and detect any possible errors accordingly. For the detailed steps, you can refer to this article: Reconcile an account in QuickBooks Online.

Let me know in the comments if you have other concerns about categorizing a refund in QBO. Do you need to run your financial reports in the program? I'll be here to help you out.