You're already on a payment plan, so you may be able to claim hardship in order to avoid them from taking the majority of your paycheck.
There is also the OIC (Offer In Compromise).
An offer in compromise allows you to settle your tax debt for less than the full amount you owe. It may be a legitimate option if you can't pay your full tax liability, or doing so creates a financial hardship. We consider your unique set of facts and circumstances:
Ability to pay;
While your offer is being evaluated:
Your non-refundable payments and fees will be applied to the tax liability (you may designate payments to a specific tax year and tax debt);
A Notice of Federal Tax Lien
may be filed;
Other collection activities are suspended;
The legal assessment
and collection period is extended;
Make all required payments associated with your offer;
You are not required to make payments on an existing installment agreement; and
Your offer is automatically accepted if the IRS does not make a determination within two years of the IRS receipt date.
You can refer to the following IRS webpage for more information regarding the OIC.