Thanks for posting here, 6dark6weird6-gma.
Though QuickBooks Self-Employed tracks income from the products and services you sell, it doesn't automatically calculate sales tax.
You can track it manually by adding a sales tax line item each time you need to collect sales tax. Also, there's no report in QuickBooks Self-Employed that shows your sales tax liability. You'll want to review the invoices you manually added sales tax to.
Please check this link for more details: Manually track sales tax in QuickBooks Self-Employed.
I'll be here if you have more questions. Wishing you all the best!