Hi, @Rexndex.
Appreciate you for posting your concern here in the Community. Let me share some insights about the tax calculation in QuickBooks Online (QBO).
Intuit wants to make sure our customers are compliant with their state and IRS guidelines. QuickBooks will calculate the taxes depending on the information you put for your employees. This information is the vital factors since they greatly affect the taxable wages of the employees on where the taxes are calculated.
To verify the calculation of your taxes, I recommend contacting our QuickBooks Online Support Team. They have additional tools to pull up your account and do a screen-sharing. They can also process an adjustment if they found out that there's a discrepancy with the calculation of your taxes.
You can contact our customer support through this link: Contact the QuickBooks Online Customer Support team.
For future reference, you can visit these article to learn more about the taxes in QBO:
Please know that you're always welcome to post if you have any other concerns about the payroll taxes. Have a good one.