How do I set the Bill No. to tell me this number has already been used?

Not an option in QBO, the bill number is usually automatically filled in by QB, or you enter the vendor bill number

Thanks for checking in with us here in the Community, dwade1.

QuickBooks offers a user-friendly option for setting up your account, allowing you to get a prompt when a bill number is being used twice. You can enable this feature through your Account and settings section.

Here's how:

1. Click the Gear ⚙ icon at the upper right corner and choose Account and settings.
   
2. Go to the Advanced panel.
3. Scroll down to Other preferences.
4. Enable the option to Warn if duplicate bill number is used.
5. Tap Save.
6. Hit Done.
   

Once turned on, QuickBooks will notify if a bill number you're using is already in the system. See the sample screenshot below.

I'll be sharing with you this article: Enter and pay bills. This will provide you different ways on how to pay your bills in QuickBooks Online as well as their outlined steps. Also, you can get more information on how to apply for partial credits.

If I can be of help while working in QuickBooks, please let me know. I'll be here to help. Have a good one!

is there any possible to customize the bill No.? For example, QBO give the bill No as ac12345, but our client wants the bill No could be 2345 automatically.

Good day, okhere.

The bill number is automatically filled in by QuickBooks Online (QBO), yet you can still manually enter the vendor bill number and put 2345 instead of 12345.

Learn more about managing bills for vendors in QBO by visiting the following articles: Enter bills and record bill payments in QuickBooks Online.

You may want to run the Bills and Applied Payments report to review the bill transactions entered. To do this, just go to Reports and enter  Bills and Applied Payments in the search bar.

I'm also adding our easy-to-access articles, webinars, and video tutorials that will help you in familiarizing the different tasks, features, and functions of QBO:

• All QuickBooks Tutorials.​
• QuickBooks Webinars.
• Help Articles.

If I can be of help while working in QuickBooks, please let me know. I'll be here to help. Have a good one!