Glad to have you here in the Community, @jodie-norman99-g.
Let me provide some information on how QuickBooks calculates your estimated taxes.
Your self-employment taxes are base on your recorded business-related income and spending, allowable expenses, and the information you have set up in your Tax Profile.
To make sure your estimated tax is accurate, you'll want to review the information entered in your Tax Profile settings. And ensure you categorize the transactions correctly.
I'm adding these articles for more details:
Most importantly, I'd recommend consulting with your accountant so you'll be guided in selecting the proper categories for your transactions.
Please let me know if you need clarification about this, or there's anything else I can do for you. I'll be standing by for your response. Have a great day.