I would like to migrate data from desktop QBi started with upload invoices from 2018 and i have error that tax is not calculated? how to upload those invoices?

By following these instructions, your invoices from QuickBooks Desktop will be uploaded to Online with ease, @jkwasik-gmail-co!

Before that, allow me to share information on why you’re getting an error message when trying to upload invoices.

If these invoices are associated with sales tax, importing them to QuickBooks Online is unable at the moment. You can utilize a third-party application to upload them. Consider visiting our Apps Center to look for the tool that works best for your business.

On the other hand, if you wanted to move multiple invoices at once without sales tax on it, follow these steps below:

1. Select the Gear icon and choose Import Data.
2. Choose Invoices.
   
3. Select Browse.
   

QuickBooks will automatically number the invoices for you in case the Custom transaction number feature is off.

After, you may pull up and customize the Transaction List by Date report to show the invoices without sales tax and then manually add the sales tax on them. Please refer to these instructions:

1. Go to the Reports menu at the left panel.
2. Enter Transaction List by Date on the search bar.
3. Click Customize, then filter the date period.
4. Select Change columns under Rows/Columns and then put a checkmark on Tax Amount.
5. Select Run report

Feel free to fill me in if you have any other questions about the processes I’ve mentioned. I'm always here to help you out. Take care and keep safe.