Very new to quickbooks online ,Ive entred a expense and applied 20% VAT yet the printed total says 17.5% ,either way the total not correct

The incorrect calculation might have caused by a browser-related issue, jason-trueman. 

I also check our list of reported issues and didn't see any similar ones. We can perform a few troubleshooting steps to correct the calculation. Let me show you how: 

1. Log in to QuickBooks through a private browser and then create and expense with 20% VAT. 
2. If it calculated correctly, we can go back to your main browser and clear its cache. This helps us remove stored files that caused QuickBooks unexpected behavior. 
3. You can also use other browsers since the store different cache files. 

You can check out these article for more details about VAT: 

• Set up and edit VAT settings, VAT codes and VAT rates
• Common VAT Codes

Always know the Community is here if you need more help!