How Illinois Tax Liens Work
Illinois is a tax lien state operating under the Property Tax Code, 35 ILCS 200/21-115 et seq. When property taxes go unpaid, the county collector (typically the county treasurer) holds an annual tax sale where investors purchase tax liens. The investor pays the delinquent taxes and earns penalty-based interest while the owner has a statutory redemption period to repay. Illinois's 36% maximum rate is the highest in the United States.
Bid-Down Interest
Illinois uses a bid-down-the-penalty format. Bidding starts at the statutory maximum — 36% for most liens — and investors compete by accepting lower rates. The lowest bidder wins. In large urban counties, rates on desirable residential parcels are often bid near 0%. In rural downstate counties, rates frequently hold near the maximum with minimal competition.
Penalty-Based, Not Annual
Illinois interest is structured as a penalty applied every 6 months, not a simple annual rate. The 36% maximum means up to 18% per 6-month period. If a lien is redeemed in less than 6 months, the full 6-month penalty still applies. This means even very short redemptions earn a minimum of the bid rate × the first 6-month period — a meaningful floor that protects investors.
2–3 Year Window
The redemption period in Illinois depends on property type: 2 years for most improved residential property, and 3 years for vacant lots, commercial property, and farmland. After the redemption period, the certificate holder may petition the circuit court for a tax deed — a court-supervised process that can take several additional months beyond the redemption deadline.
SB75 Subsequent Tax Buyer
Illinois allows certificate holders to pay subsequent year taxes on the same property, adding them to the existing lien. This is called the Subsequent (or "Sub") Tax program. Each subsequent payment accrues at the same bid rate and extends the investor's lien position. It is a powerful tool to protect against redemption by a competing investor and to compound returns on a single parcel.
Scavenger sales: Properties with two or more years of delinquent taxes that did not sell at the annual tax sale are offered at a Scavenger Sale held every two years. Bids at Scavenger Sales are made as a percentage of the taxes owed — bids can be as low as $250 plus costs. The redemption period after a Scavenger Sale purchase is shorter: typically 6 months for unimproved property, 2.5 years for improved. Cook County holds its own separate Scavenger Sale cycle.
Notice requirements: Illinois requires certificate holders to serve formal notice on the property owner and any lienholders before the redemption period expires. Failure to serve proper notice can void your petition for a tax deed. Strict compliance with 35 ILCS 200/22-5 through 22-30 is mandatory. Most investors working toward tax deed petitions hire an attorney experienced in Illinois tax deed proceedings.
Subsequent taxes: Paying subsequent year taxes is optional — not paying them does not void your original lien, but another investor can purchase the subsequent taxes and gain a competing lien position. Always evaluate whether subsequent taxes are worth paying on each parcel in your portfolio.
Indemnity fund: Illinois maintains a tax sale indemnity fund that compensates investors who lose certificates due to government error. This provides a meaningful backstop — a feature not present in most lien states.
Cook County operates under different rules and timelines. It is the most complex tax lien environment in Illinois and one of the most competitive in the nation. The annual tax sale is held online, and institutional buyers dominate — rates on most desirable parcels are bid near 0%. The Scavenger Sale (held every 2 years) offers more accessible opportunities at deeply discounted prices.
Cook County's tax sale is administered separately from the rest of Illinois. The Cook County Treasurer's office runs its own online portal (cookcountytreasurer.com). The annual tax sale typically runs in November; the Scavenger Sale is typically held in even-numbered years. Cook County also has unique rules around the SB75 subsequent buyer program and notice procedures — consult county-specific resources before participating.
For individual investors: The high-yield, lower-competition opportunity in Illinois is downstate — not Cook County. Counties like Peoria, Rock Island, Sangamon, McLean, and rural southern Illinois counties regularly produce rates above 18% with minimal institutional competition.
The Illinois Tax Lien Process
From delinquency to certificate purchase to redemption or tax deed — the full Illinois cycle.
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1Taxes go delinquent after June 1 (first installment) or September 1 (second installment) — Illinois property taxes are paid in two installments. Taxes not paid by the due date accrue a 1.5% per month penalty. After the second installment deadline, the county collector prepares a list of delinquent properties to be offered at the annual tax sale. This list is published publicly — usually available on the county website or treasurer's office weeks before the sale.
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2Register with the county collector's office — Most Illinois counties require advance registration to participate in the tax sale. Registration deadlines vary by county — some require registration weeks in advance, others allow same-day. Many larger counties (including Cook) require online registration and advance deposit funds. Contact each county treasurer's office directly or check their website for current-year registration requirements.
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3Research parcels before the sale — Download the delinquent parcel list and evaluate each property: type (residential, vacant, commercial, farmland), assessed value, existing encumbrances, owner status, environmental risk, and condition. Illinois's 2–3 year redemption window means you'll hold the lien for a meaningful period — make sure each parcel is worth the wait. Pay particular attention to IRS federal liens, which survive most state lien proceedings.
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4Bid at the annual tax sale (October–November) — Illinois tax sales are typically held in October or November. Most counties now use online bidding systems, though some smaller counties still conduct in-person sales. Bidding starts at 36% and is bid downward. Set your minimum acceptable rate for each parcel before the sale — the fast pace of bidding makes in-auction decisions unreliable. Bring or pre-load funds equal to the total taxes you plan to pay.
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5Pay the delinquent taxes and receive your certificate — After winning a bid, you pay the outstanding taxes (your investment principal) plus any applicable fees. The county issues a Certificate of Purchase. Store this document securely — it is the evidence of your lien position and will be required for any subsequent tax proceedings. Payment is typically due on the day of sale or within 24 hours.
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6Monitor and optionally pay subsequent taxes — Each year during the redemption period, evaluate whether to pay subsequent year taxes on your parcels. Paying subsequent taxes adds to your lien principal and accrues interest at your original bid rate. Failure to pay subsequent taxes means another investor can purchase them and hold a competing position — this does not void your original lien, but complicates any eventual tax deed petition.
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7Redemption or petition for tax deed — When the owner redeems, you receive your principal plus accrued interest calculated at your bid rate on a 6-month penalty cycle (minimum of one full 6-month period even for early redemptions). If the property is not redeemed by the end of the statutory period, you may petition the circuit court for a tax deed. This is a court proceeding — proper notice must be served on the owner and lienholders, and the process can take 3–9 additional months after the redemption deadline. Most investors in this situation hire an Illinois tax deed attorney.
All 102 Illinois Counties
Search, filter, and sort every Illinois county. Click any row to expand full details including auction timing, contact information, and investor notes. All 102 counties hold annual tax sales — most in October or November.
| County | Population | Max Rate | Auction Month | Region | Competition |
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