The last step in the IRS enforced collection process involves a levy. If you have ignored all attempts by the IRS to either negotiate repayment or paid your unpaid tax bill in full, the IRS will slap you with a Notice of Levy.
This notice allows the IRS to legally take all or any of your personal and real property in order to satisfy your unpaid tax bill. In addition to currently owned property, the levy notice will apply to any future interest you may receive in property.
Any property you have that was previously subjected to a tax lien, will not have a tax levy. (One piece of property cannot have two liens placed on it). This entire process could have been negated if only you would have contacted the IRS willingly.