I've paid extra tax on 2020, it's showing even in the app here $1600 - I owe $0 wondering if I would get this money back or how would that work?

Great to have you here, Kemomanpop.

At the end of the fiscal year when you know how much profit you actually made, you'll pay any remaining taxes or get money back for overpayments. In some cases, the IRS may identify the overpayment and send you a notice in the mail. This explains the situation and advises you as to what actions you need to take. You may also request a refund directly from an IRS agent over the phone. 

However, if your estimated tax payment is $0, it means you didn't make a profit for that quarter. Just in case you made money, let's make sure you entered and categorized all of your business transactions. When you file your taxes, you still need to report quarters when you didn't make a profit. For more details about this one, see the How QuickBooks Self-Employed tracks self-employment taxes article. 

You can check out these articles to learn more about recording taxes in QBSE:

• Self-Employment Taxes.
• How can QuickBooks Self-Employed help me manage my taxes and forms?

If you need further assistance with handling your self-employed taxes, you may reach out to our representatives. Here's how to contact QuickBooks Self-Employed Support.

Please touch base with us here if there's anything else you need in QBSE, I'm determined to ensure your success. Take care always.