The first thing you need to do is to hire the services of a well-reputed tax professional that has a lot of experience dealing with IRS debt. You may be tempted to handle the debt on your own, but when a lot of money is involved, it is best to get a professional involved. Determine whether your tax professional charges on hourly rate, or if he asks for a flat fee. Do not make your final selection until you have contacted three-to-four tax professionals. In the end, it really comes down to you to judge if the tax professionals looks like someone who will work hard on your case and put in a great deal of effort to negotiate your case with the IRS.
You will need to prove your tax professional with copies of your past taxes. He will go over them to ensure that you have not overlooked any past deductions. If he finds something that you may have overlooked, he can use it to file for an amendment on your behalf. Getting your past tax amended will reduce your overall debt reduced, consequently decreasing the amount of debt you owe to the IRS.
Assist your tax professional by creating a detailed budget and providing it to him. You need to provide a proof of your income to your tax professional as well. He will use the information regarding the budget and sources of income provided by you to determine if you can afford to repay the debt that you owe to the IRS. You need to be completely honest with your tax professional when discussing your budget and source of income, as he will be using this information to negotiate with the IRS on your behalf.
Now that your tax professional has all the details that he needs, you both can start discussing the best possible options to repay the debt. If you are short on money, he can negotiate with the IRS and get it to agree on accepting payments in instalments. If you have enough cash available, he can try to make arrangements for a lump sum payment after convincing the IRS to reduce the amount of debt owed by you.