Hi there Juan Gonzalez.
It's important that all your information is entered correctly so that your books can be well-balanced. QuickBooks Online is a great tool able to help you keep track of sales tax so you know the amount owed to the government. I can provide some information about custom taxes.
In QuickBooks Online Canada, the sales tax can't be tracked for the US the same as it would for Canadian provinces. You can add a custom tax rate that can collect money in an account in your chart of accounts, but there won't be the option to map it as detailed as it s for each line of the Canadian sales tax filing. You can add a custom tax by following the steps in this article, in the Custom sales tax section.
if you have any other questions, feel free to reach out here.
