Federal tax liens can really make your life miserable! When your taxes are not paid the IRS establishes a lien against all of your assets (especially real estate). This gives the IRS the legal right to collect taxes from the sale of your assets, which includes just about everything you own.
Liens filed against you by the IRS also show up on your credit report and often prevent you from opening a checking account or borrowing against any assets, like your home. The existence of tax liens may also prevent you from being able to obtain credit at a reasonable rate of interest.