How to File a Mechanics Lien in Illinois: A Step-by-Step Guide for Contractors and Subcontractors

A mechanics lien is one of the most powerful tools available to contractors, subcontractors, and suppliers who have not been paid for work performed on an Illinois construction project. It attaches a security interest to the property itself, giving the unpaid party leverage that an ordinary breach of contract claim does not provide. If the lien is enforced through foreclosure, the property can be sold to satisfy the debt.

But the Illinois Mechanics Lien Act (770 ILCS 60) imposes strict requirements on who can file, when they must file, and what the lien claim must contain. Miss a deadline by a single day, omit a required element, or fail to send the right notice, and the lien can be invalidated entirely - even if the underlying debt is undisputed. Illinois courts have consistently held that the Mechanics Lien Act is in derogation of common law and must be strictly construed.

This guide walks through the complete mechanics lien filing process in Illinois - from the initial notice requirements through recording and enforcement - so that contractors and subcontractors can protect their payment rights without making the mistakes that get liens thrown out. That said, given how strictly Illinois courts construe the Act, having an experienced mechanics lien attorney prepare and file the lien is strongly recommended. A single technical defect - a wrong legal description, a missed notice, or an overstated amount - can cost you the entire claim.

Who Can File a Mechanics Lien in Illinois?

Under Section 1 of the Mechanics Lien Act, any person who furnishes labor, services, material, fixtures, apparatus, or machinery for the improvement of real property has a right to a lien on that property. This includes general contractors, subcontractors, sub-subcontractors, material suppliers, equipment lessors (where the equipment is consumed or incorporated into the work), architects, engineers, and surveyors.

The key requirement is that the work or materials must have been provided for an improvement to the specific property against which the lien is filed. The claimant must also show that the work was performed under a contract (express or implied) with the owner or with someone authorized by the owner to contract for the improvement.

Certain parties cannot file mechanics liens in Illinois. Employees who are paid wages (as opposed to independent contractors) generally cannot file a lien for unpaid wages - their remedies are under employment law, not the Mechanics Lien Act. Parties whose work does not constitute an "improvement" to real property - such as routine maintenance, cleaning, or landscaping that does not permanently enhance the property - may also lack lien rights depending on the nature of the work.

The 90-Day Subcontractor Notice Requirement

This is where most subcontractors and suppliers lose their lien rights. Under Section 24 of the Mechanics Lien Act, any party who does not have a direct contract with the property owner must serve a written notice on the owner within 90 days of the date they last furnished labor, services, or materials.

The notice must identify the subcontractor or supplier, describe the nature of the work or materials furnished, identify the contractor who hired them, and state that they have a claim for payment. The purpose is to alert the owner that someone other than the general contractor has a potential lien claim against the property - because the owner may not otherwise know that subcontractors or suppliers are involved.

If the subcontractor fails to serve this notice within 90 days of their last date of work, the lien is limited to the amount the owner owes the general contractor at the time the notice is received. In many cases, if the owner has already paid the general contractor in full, a late notice means the subcontractor's lien has no practical value.

General contractors with a direct contract with the owner are not required to send a Section 24 notice. Their right to file a lien exists by virtue of the direct contractual relationship. But subcontractors, sub-subcontractors, and suppliers must comply with this requirement or risk losing their lien rights entirely. For more on how timing affects your lien, see our article on what counts as the last date of work.

What Must Be Included in a Mechanics Lien Claim

Section 7 of the Mechanics Lien Act specifies what a lien claim must contain to be valid. The claim must be in writing and must include:

The name of the lien claimant (the person or company asserting the lien).

The name of the owner of the property (or the name of the person who contracted for the improvement, if different from the owner).

A description of the property sufficient to identify it. This typically means the legal description of the property as it appears in the county records - not just the street address. Using only a street address without the legal description or PIN can be grounds for invalidation.

The amount due and unpaid. This must be an honest, good-faith statement of what is owed. Intentionally overstating the lien amount is a serious problem - Illinois courts have held that a willfully overstated lien may be invalid in its entirety, not just reduced to the correct amount.

The date the claimant last performed work or furnished materials. This date is critical because it establishes the lien's priority and the running of deadlines.

The lien claim must also be verified - meaning the claimant (or an authorized agent) must sign it under oath or by affidavit. An unverified lien claim is defective.

The Four-Month Recording Deadline

Once the work is complete, the clock starts running. Under Section 7 of the Mechanics Lien Act, the lien claim must be recorded with the county recorder in the county where the property is located within four months after the claimant's last date of work in order to be perfected - meaning it has full priority against all parties, including subsequent purchasers and lenders. A lien recorded after four months but before two years from the last date of work is still enforceable against the original property owner, but it loses priority against third parties. This distinction matters: a lien without priority is subordinate to existing mortgages and any interests recorded before the lien, which in most cases means there is little or no equity available to satisfy the claim. If the property has been sold or refinanced, the lien may be worthless entirely. The safest course is always to record within the four-month window.

For subcontractors who have served the required 90-day notice, the four-month deadline runs from their own last date of substantive work - not from the date the overall project was completed. This means a subcontractor who finishes early on a long project could see their lien deadline expire months before the general contractor's work is done.

What counts as the "last date of work" matters enormously. Illinois courts have held that punch list work, warranty repairs, and return trips to fix defective work generally do not extend the deadline. Only substantive work that advances the project counts. Contractors and subcontractors should track their last date of meaningful work carefully and not assume that minor callbacks will keep the deadline alive.

Where and How to Record the Lien

The lien claim is recorded with the recorder of deeds in the county where the property is located. Recording requirements vary slightly by county, but generally the claim must be a legible, signed original (or certified copy) that meets the county's formatting requirements for recorded documents.

After recording, the claimant should serve a copy of the recorded lien on the property owner. On owner-occupied single-family residences, this is mandatory - Section 7 requires the contractor to give the owner written notice within 10 days after recording. If timely notice is not given and the owner suffers damages as a result, the lien is extinguished to the extent of those damages. On other project types, serving the owner after recording is good practice even where not strictly required, as it puts the owner on formal notice and strengthens the claimant's position in any enforcement action.

Recording fees vary by county - in Cook County and the collar counties, expect to pay between $40 and $100 depending on the number of pages. The fee is a minor cost relative to the protection the lien provides.

The Contractor's Sworn Statement

Under Section 5 of the Mechanics Lien Act, before a contractor receives payment, the owner can require the contractor to provide a sworn statement listing all subcontractors, material suppliers, and other parties furnishing labor or materials on the project, along with the amounts due or to become due to each. Any payment the owner makes to the contractor after receiving a subcontractor's notice - without retaining sufficient money to cover outstanding claims - is considered an illegal payment under the Act and does not extinguish the subcontractor's lien rights.

On owner-occupied single-family residential projects, Section 5 imposes an additional requirement: subcontractors and suppliers must serve a written notice on the occupant within 60 days of their first day of work, identifying themselves, the work being performed, and the contractor who hired them.

For subcontractors, the sworn statement is significant because it puts the owner on notice of who is working on the project and how much is owed down the chain. When combined with the Section 24 notice, it creates a paper trail that protects everyone's interests. For more on how lien waivers interact with your lien rights, see our detailed guide.

Common Mistakes That Invalidate a Mechanics Lien

Illinois courts strictly construe the Mechanics Lien Act, and technical defects can be fatal. These are the mistakes that most commonly result in a lien being invalidated or unenforceable:

Missing the 90-day subcontractor notice. This is the single most common reason subcontractor liens fail. If you do not have a direct contract with the owner, the Section 24 notice is not optional.

Missing the four-month recording deadline. Even a single day late can cost you priority. Track your last date of substantive work and calendar the deadline with margin to spare.

Using an incorrect or incomplete property description. The legal description must be accurate and sufficient to identify the property. A street address alone may not be enough. Pull the legal description from the county recorder's records or the title commitment before preparing the lien claim.

Overstating the lien amount. Include only amounts that are actually due and unpaid. Do not inflate the claim to include disputed charges, future work, or amounts already paid. A willful overstatement can void the entire lien.

Failing to verify the claim. The lien must be signed under oath or by affidavit. An unsworn lien claim is defective.

Filing against the wrong property. On projects involving multiple parcels, common areas, or subdivisions, make sure the lien is recorded against the correct PIN and legal description.

Failing to serve the owner after recording. On owner-occupied single-family residences, failure to notify the owner within 10 days of recording can extinguish the lien to the extent of any resulting damages.

Because of how strictly Illinois courts enforce these requirements, having an experienced mechanics lien attorney draft and file the lien claim is strongly recommended. The cost of professional preparation is a fraction of what you stand to lose if the lien is thrown out on a technicality. An attorney can verify the legal description, confirm the correct parties, ensure proper verification, and handle service - all of which reduce the risk of a defect that could cost you your claim entirely.

For more on how property owners and contractors can attack defective liens, see our article on how to challenge a mechanics lien in Illinois. For more on the removal process from the property owner's perspective, see our guide on removing a mechanics lien in Illinois.

What Happens After You File

Filing the lien is not the end of the process - it is the beginning of the enforcement window. The claimant must file a lawsuit to foreclose the lien within two years of the last date of work. If no foreclosure suit is filed within that period, the lien expires and becomes unenforceable.

Be aware that this window can be dramatically shortened. Under Section 34 of the Mechanics Lien Act, the property owner can serve a written demand requiring the lien claimant to file suit within 30 days. If the claimant fails to file within 30 days of receiving a Section 34 demand, the lien is forfeited. This is a powerful tool for property owners and a serious trap for lien claimants who are not monitoring their deadlines.

A mechanics lien foreclosure action is a lawsuit filed in the circuit court of the county where the property is located. The claimant must prove that it performed the work, that it was not paid, that it complied with all statutory requirements (notice, recording, verification), and that the amount claimed is accurate. If the court finds in the claimant's favor, it can order the property sold at a judicial sale to satisfy the lien.

In practice, most mechanics lien disputes settle before trial. The lien itself is often sufficient leverage to bring the property owner to the negotiating table, because a recorded lien clouds the title and can prevent the owner from selling or refinancing the property until the lien is resolved. This is why filing correctly matters so much - a technically defective lien loses that leverage entirely.

For additional answers to common lien questions, visit our mechanics liens FAQs page.