Thanks for joining this thread, @Andreas.

You'll have to turn on the function, so the IIF files that are imported will continue to process. Also, make sure to use the Export Preferences page to enter your QuickBooks accounts. Use the same names of the QuickBooks accounts you will use for the payroll data. let me show you how.

1. Go to Setup.
2. In the Payroll and Services section, select Preferences.
3. Select QuickBooks Desktop for Windows (IIF) as your accounting software.
4. Select Next to proceed.
5. In the Checking Account field, enter only the name of the bank account exactly as it appears in your QuickBooks Chart of accounts.
6. Select OK and the default accounts listed will be created automatically in your QuickBooks. But if you already have accounts created specifically for payroll transactions, select Customize to enter the account names exactly as they appear in your QuickBooks.
7. Select OK until your back to the Setup Overview page.

For more details, see this article: Export Intuit Online Payroll transactions to QuickBooks for Windows or Mac (IIF).

Once done, you can now import to QuickBooks Desktop. If you have QuickBooks Desktop for Windows, you can still import transactions using IIF files. Follow the steps on how to import the file:

1. Sign in to your company file as an admin. Make sure you're in a Single-user mode. 
2. Go to the File menu, then select Utilities.
3. Look for Import, then click Import IIF.
4. Select the IIF file you want to import, then select Open.
5. Click OK to confirm the import.

For QuickBooks for Mac, these steps would let you import the file:

1. Sign in to your company file as an admin.
2. Go to File, then select Import.
3. Select From IIF Files, then export your IIF file.

Check out this article for additional reference: Export, Import, and Edit IIF Files.

To learn more about importing these files, and the maximum number of entries allowed, you may check out these articles:

• IIF Overview: import kit, sample files, and headers
• Maximum number of QuickBooks Desktop list 

Please don't hesitate to reach back out to us if there's anything else you need. We're always here to help. Have a good one!