If you are unable to settle the tax debt through an Offer in Compromise or can't pay the agreed amount on your accepted Offer in Compromise, than you may do well to to look into setting up a payment plan.  A Payment plan can stop the harassing calls and letters from IRS agents and stop the progression of any bank levies or liens.

The IRS can be accommodating when setting up a payment plan and can be a good lead in for other settlement services.