If you owe back taxes, your first option is to set up an installment agreement with the IRS, which you have already done.
Some companies (such as those you mentioned) offer to arrange with the IRS to settle your debt for a portion of what is owed. These may often be deceptions. Essentially, they help you make an "offer in compromise" (OIC) to the IRS. An OIC is viewed as a last resort, and many proposals are not successful. To see if a compromise is possible for you, use the checklist in IRS form 656 "Offer in Compromise" to see if you meet the income requirements. If you do, complete form 656A. If you qualify, there is a $150 application fee. If you hire someone to help you, you will also be paying the company for redoing the taxes for the years where you underpaid, as well as their time, so there may be considerable costs involved.
Other restrictions apply, so be sure to read all relevant IRS information completely. IRS forms are available from the IRS Web site at www.IRS.gov.
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