If Invoice was paid by mistake after client cancelled service, How should I go about fixing/recording the already marked as paid invoice and payment?

You've come to the right place, lacutsocala. I'm here to help you record it as bad debt in QuickBooks Online.

The term bad debt usually refers to accounts receivable that will not be collected. I'll guide you through the process of how we can write this off in QBO.

First, we'll need to create a bad debt expense account. Here's how:

1. From the Accounting menu, select Chart of Accounts.
2. Select the New button.
3. From the Account Type drop-down menu, select Expense.
4. From the Detail Type drop-down menu, select Bad Debts.
5. Enter Bad Debts in the Name field.
6. Select Save and close.

Next, we'll create a bad debt item. Here are the steps:

1. Go to Settings ⚙ and select Products and Services.
2. Select New, and then Non-inventory.
3. In the Name field, enter “Bad debts.”
4. From the Income account ▼ drop-down, select Bad debts.
5. Select Save and Close.

You can go directly to Step 4 and Step 5 in this article to continue with the process: Write off bad debt in QuickBooks Online.

If you need anything else, please let me know by adding a comment below.