It is always a good idea to understand how a tax debt may be relieved, and what options are available for you.
In most cases, the amount owed to the IRS is a money issue, and does not cross the line to being a criminal matter of being charged with tax evasion. The IRS will charge interest and penalties on the tax debt, so its critical to try to resolve the issue, through a settlement or quickly paying the debt, before the amount increases beyond your control. The IRS debt is special and should be thought of as having more issues than other debts since the IRS can take money from you bank account, or take your wages when you owe them, and they can do all of this without your permission.
The IRS trains their collection people well, so once they get assigned to your case there will be a lot of work to resolve the matter and they will make your life unpleasant. They will send a ton of notices, and even come to your home to interview you. Its best to be polite, but do not give them any detailed information and tell them you need to hire a tax attorney to resolve the issue. They will request financial information in the Form 433-A, which is for individuals, or the Form 433-B, which is the form for businesses. Along with these forms that will require the last six months of your bank statements, and information to verify your income and expenses, such as copies of bills, mortgage payments, pay stubs etc.