how to find my last year tax that I collect from customer

You can generate the Taxable Sales Summary report to view a detailed breakdown of the sales tax collected from your customers, @dubaitrad.

Here's how:

1. Navigate to the Reports tab in the left-hand menu.
2. Enter Taxable Sales Summary in the search field and select it.
3. Click on the Net Amount to open the Transactions Report.
4. Adjust the Report period and click on Columns.
5. In the Columns section, add the Customer option to view the tax collected for each customer.

You can check this article to learn more about reports: Run a report in QBO.

I'll also add this article to get the most out of your financial reports: Customize reports.

The Community is here to help you out if you have further questions.