Should some check numbers over a 3 month period change, why? Bank reconciliations for same period have correct check numbers. Will this happen often?

Hi Megan.

I appreciate you for raising your concern here on the Community page.

The system won't make changes to your check numbers unless a user had modified them. You can visit your Audit Log to see each change made to your transactions. I'll guide you how.

1. Open your QuickBooks Online (QBO) account, then go to the Gear icon.
2. Click on Audit Log under Tools.
3. Check for the possible updates made to your checks or check numbers.

If necessary, input the old numbers to correct them.

Just in case you don't trace any updates made manually, you may connect with our Support Team so a representative can review this further and investigate the root cause of the issue.

Here's how to contact support:

1. Sign in to your QuickBooks Online company.
2. Select Help (?).
3. Select either tab to get started:
   • Assistant: Get quick, personalized answers. Select a suggested option, or type a question or topic you need help with. If you decide you need further help, you can still Talk to a human.
   • Search: Search the QuickBooks Online knowledge base directly, or select Contact Us and choose a way to connect with us:
     • Start a chat with a support expert.
     • Get a callback from the next available expert.

Our live support is available every  M-F 6 AM to 6 PM PT and Saturday 6 AM to 3 PM PT for QBO Simple Start, Essentials, and Plus. And, any time or any day for QBO Advanced.

I'm adding this link for more hints about handling checks in QBO: Create and record checks in QuickBooks Online.

Moreover, you can check out the topics from our help articles for other resources while working with QuickBooks in the future.

If you have any other questions about checks, let me know by adding a comment below. I'm always here to help. Have a good one!