Welcome aboard in the Online Community. Getting your payroll taxes properly recorded in your account is what I aim for.
When you’re switching to QuickBooks Online Payroll from a previous payroll provider, you'll be asked to enter quarterly totals of taxes. This information is important since some annual payroll tax forms require a breakdown of your totals by quarter.
If you're previously using a payroll provider, you need to run the Payroll Summary Report to get the detailed deduction for your employees’ Social Security and Medicare. I suggest, customizing the report by quarter to get the accurate breakdown.
However, if you manually wrote the checks, you'll need to determine how much the taxable wages are and multiply them by the Social Security and Medicare rates. Check out this link for the detailed instructions: https://www.irs.gov/taxtopics/tc751.
To help you get started with using the Payroll feature, check out these articles: