IRS letter explained

IRS Letter 3172: a tax lien was filed

Letter 3172 tells you the IRS has filed a Notice of Federal Tax Lien, a public claim against your property. It also gives you a time-limited right to a hearing.

UrgencyUrgent
What it isNotice that a lien was filed
Time to respondBy the date on the letter (about 30 days)
Your rightA Collection Due Process hearing