Hi @mana5,
Welcome to the Community. I'm here to help you fix the error when importing data in QuickBooks for Mac.
Currently, the option to override the imported checks is unavailable. If what you meant by the error is incorrect information in transactions, you'll need to edit them individually.
Right now, the ability to update information by batch is not yet possible. To learn more about how to make changes to existing transactions, you can check out this page: View and edit transactions in QuickBooks Desktop for Mac.
If you're referring to a different error, I recommend adding more details below. This way, we'll be able to get back to you with more accurate information.
For additional reference, I've attached a link you can use to learn more about what you can do with Intuit Interchange Format (IIF) files: Export, import, and edit IIF files.
Keep us posted if you need anything else regarding fixing paycheck errors. Have a great day.
