What version of QuickBooks are you using? Is it the United States version or another country? I need this information to help you set up your sales and purchase taxes accurately.
If you have the UK version, you can create a tax item for sales and purchases. Here's how:
Go to the Taxes menu then select VAT tab.
Find and lick the Add tax button.
Enter the Tax Name and Description.
Under Tax Agency mark the Sales and Purchases box then add the correct rate. See the sample screenshot below:
Enter all the required information, then hit Save.
Once you use this item on your income and expense transactions, you can keep track of its trend by pulling up a VAT Detail report. This statement shows all sales and purchase entries. Follow these steps:
Go to Reports.
In the search box, enter VAT Detail Report and then select it.
Select a report period and the date range.
Hit Run report.
If you're referring to a different version, please let me know in the comment section below. I'll be more than happy to share further insights about tax tracking in QuickBooks Online. Have a nice day!