Hello NC3,
Thanks for reaching out about this. Being able to import your data from another software via an app in QuickBooks Desktop is a great way to make sure all your business accounting information is gathered in one place.
When it comes to transaction numbers, QuickBooks Desktop does allow you to add more than 10 digits, however it's important to note that it won't count up in the sequence when you have 10 or more digits to your number. Rather, creating a new entry would set the transaction number back to one. With this in mind, it could by why you're having trouble importing the files that have transaction numbers with 11 digits.
I know being able to import your transactions is a great way to cut down on the work involved when it comes to recording your transactions. I recommend using shorter numbers to be able to continue importing or manually entering the transactions will also facilitate getting those details in QuickBooks Desktop.
Learn more about IIF files here: Export, import, and edit IIF files
I welcome you to submit feedback about this by going to the Help menu and choosing Send Feedback Online. It's the perfect way to let our product development team know the features that would help you with managing your books in QuickBooks Desktop. Many of the suggestions made by users like you have become features in the program.
I'm here if you have further questions. Enjoy the rest of your day. :)
