Work from a vendor done wrongly and paid to a second vendor. How to reduce first vendor bill with the amount paid to the second vendor?

Thank you for providing us with in-depth details of your concern, Annamaria. We can use a clearing account to help correct the amount entered in that bill.

Since you've paid vendor A of the reparation cost, it has been closed and you don't want to touch it anymore. To pass on half of the amount, you are correct that you need to add Vendor A as a customer. Then, make Vendor B's bill billable to it so you can invoice it. Next, record an invoice payment deposited to a clearing account, and then, pay Vendor B's bill against it.

Let's temporarily utilize a clearing account to decrease the first vendor's bill with the amount paid to the second vendor. Before doing so, I'd recommend consulting your accountant for advice. They can share another way to account for these transactions accurately. 

Follow these steps to create the account:

1. On the left panel, go to Transactions.
2. Navigate to the Chart of Accounts tab, then click the New button.
3. In the Account window, choose Bank as the Account Type.
4. Enter Clearing Account, Barter Account, or Wash Account in the Name field.
5. Leave the Opening Balance field blank, then hit Save and Close.

After that, proceed with recording the Journal Entry for Vendor B:

1. Go to the + New button and choose Journal entry.
2. Select the Journal date.
3. In the first line, select the Accounts Payable account and enter the amount in the Credits column. Then, select Vendor A from the Name field
4. Add the wash or barter account you've created on the second line and enter the amount in the Debits field.
5. Hit Save and close.

Once done, create another Journal entry for Vendor A. Ensure to debit the Accounts Payable account and credit the wash or barter account. Finally, apply the journal entry as a payment to Vendor A's bill.

I'm adding this article to record business expenses: Enter bills and record bill payments in QuickBooks Online.

Furthermore, save this guide for details on running a report that reflects all vendor payments: Run a report with vendor totals.

Kindly leave a reply if you require additional assistance with bill payments or managing vendors. I am here to assist you through every step. Keep safe!