Hello, jaapkrijger.
I'd like to share some steps to help you with the sales tax.
The 16% rate must have been set as a default taxable code in the preferences. This is why when you duplicate an item, you still see the 16% rate instead of the !8%.
You'll want to check it out by following these steps:
- Go to Edit > Preferences.
- In the Preferences window, click Sales Tax on the left panel.
- Select the Company Preferences tab.
- Under the Assign Sales Tax Codes section, you'll see the default tax rate from the Taxable Item Code drop-down menu. You can change the rate if necessary.
- Hit OK once done.
When you duplication an item, please make sure to select the Tax Code to make sure they are correct.
In addition, let me add these articles to learn more about sales tax set up and resolve any issues if you encounter any:
I'll be right here if you have more questions related to sales tax or need help with other concerns. Have a good day ahead!