Hi chiky_17-hotmail,
Thanks for reaching out here. Welcome! QuickBooks Online Payroll automatically calculates the appropriate taxes for you, once you've set up your employees. When the calculations appear to be 'off', it's essential to review the employee set up, along with the TD1. I also suggest reviewing the Payroll Deductions Tables for CPP, EI, and income tax deductions.
Should you require additional assistance, please contact us at 1-855-253-1536 from Monday to Friday between the hours of 9 AM and 8 PM EST. We would love the opportunity to work with you in real time, and ensure your QuickBooks Online Payroll calculations are accurate, as soon as possible!
If you have any other questions, feel free to reach out again. We would be happy to help!