Not all debts are created equal. Some require more diligence to discharge. Back-taxes are one such category. The good news is that federal bankruptcy laws allow you to potentially discharge certain income tax owed to the IRS, or state division of taxation, if they are more than 3 years old. This means you may never have to pay it back. Additional rules apply.
Aside from the dischargeabilty question, ALL tax garnishments must stop instantly the moment your bankruptcy is filed. Not only will your take-home pay increase, but you are in a better position to arrange a payment plan (Chapter 13 case) for any tax debts that may not be dischargeable. Bankruptcy can also stop interest and penalties from accruing.
Clearly, tax problems must be handled effectively, or they will never go away.