It depends on so many other factors than gross income. Write offs and RRSP contributions affect what you owe.

The CPP payment is often quite high as you are required to pay both the employee and employer contributions as a self employed person. This CPP payment is often the largest part of my tax bill.

Often a provider who has been in business for awhile doesn't have major write offs other than groceries/supplies so they end up paying more tax.

You can check to make sure your accountant has used all possible deductions.