will IRS settle with you for less than you owe

Offer in Compromise

The IRS has certain procedures it must follow in order to properly assess and collect taxes. You can generally negotiate with the IRS revenue agents prior to the tax being assessed. Once the tax has been assessed and collection proceeures begin your opportunities for negotiating are pretty limited unless you are willing to go to court with the IRS, and you can negotiate a settlement with the trial attorneys rather than the revenue agents.

This following outline from a continuing education seminar gives a pretty good explanation of the IRS procedures for assessing and collecting taxes. LINK

The problem with those outfits that advertise on television is that they are generally only contacted by taxpayers after an assessment has been made. By then it is too late to negotiate. Your only avenue is the Offer in Compromise. And an OIC is not really negotiating with the IRS. It's an accept or reject offer that has to satisfy certain conditions to be approved.