Illinois legal descriptions and subdivision
Illinois legal descriptions and the Plat Act: identify the land, then test the split
A legal description identifies the land. The Illinois Plat Act addresses certain divisions of it: when an owner divides land into two or more parts and any part is under five acres, Section 1(a) generally requires a survey and subdivision plat unless an exception applies. Recognizing a description method and establishing that a proposed split is approved are different tasks.
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Which legal-description method do the words identify?
| Method | How it identifies the land | Study clue |
|---|---|---|
| Lot and block, or recorded plat | A specified lot and any block in an identified recorded subdivision | Lot 8, Block 2, named subdivision and recording reference |
| Metes and bounds | Directions, distances, monuments or other boundary calls | Beginning at a point, then following the parcel's perimeter |
| Government or rectangular survey | Section subdivisions located by township, range and principal meridian | NE quarter of the SW quarter of a specified section |
The BLM land-description specifications, chapters I and III, distinguish these approaches. A reference to a recorded plat brings its relevant features into the description; the lot number alone is not the whole reference. For example, Lot 8 in one subdivision need not be Lot 8 in another. The sample above is a recognition clue, not a complete description for a deed.
Metes and bounds: distinguish the approach from the perimeter
A point of commencement can lead from a known reference to the parcel. The point of beginning starts the actual perimeter; the two points can coincide. In a simplified example, go east 100 feet, north 200 feet, west 100 feet and south 200 feet from that beginning. The route returns to its start and encloses 20,000 square feet.
That arithmetic does not establish a legal boundary. Real descriptions may use bearings, curves, monuments, adjoining lands and exceptions. A figure can close mathematically and still identify the wrong land or omit a material qualification.
Rectangular survey: locate the larger fraction first
For the NE quarter of the SW quarter of a standard 640-acre section, first find the section's SW quarter. Then take that quarter's NE quarter. The calculation is 640 × 1/4 × 1/4 = 40 acres. The location also needs the applicable section, township, range and meridian references.
The BLM rectangular-survey explanation describes a normal township as six miles square, containing 36 sections, and a normal section as 640 acres. Its Oregon and Washington example uses the Willamette Meridian; that is not a direction to use that meridian for Illinois property. Actual survey records and fractional sections can differ from the ideal acreage.
Use the national land-description and measurement lesson for the broader measurement work.
When does the Illinois Plat Act starting rule apply?
765 ILCS 205/1(a) asks about a division into at least two parts with any resulting part below five acres. Subject to an applicable exception, the owner must have the land surveyed and a subdivision plat made by an Illinois Registered Land Surveyor. A large remainder does not cancel a smaller resulting part.
- Identify the tract and proposed division.
- Check the size of every resulting part.
- Test the exact conditions of any claimed exception.
- Check the applicable local requirements and approval process.
- Obtain the professional work and recording required for that proposal.
The Act also calls for detailed dimensions, designated public and service areas, monumentation and specified topographic information. A sketch attached to a listing does not do that work. The broker's practical role is to recognize the issue and obtain the right documents, not certify a subdivision from the acreage alone.
Which exception fits the actual division?
| Provision | Facts to check | What the label does not establish |
|---|---|---|
| 1(b)(1): parcels at least five acres | All resulting parcels meet that size; no new streets or access easements | Acreage alone satisfies every state or local requirement |
| 1(b)(2): recorded lots or blocks | Lots or blocks under one acre in a recorded subdivision; no new streets or access easements | Every division of a recorded lot qualifies |
| 1(b)(3): adjoining owners | Sale or exchange between owners of adjoining and contiguous land | Any small parcel sold to any buyer qualifies |
| 1(b)(8): historical two-part division | No more than two parts of a tract existing July 17, 1959; no new streets or access easements | Any newly proposed two-lot split qualifies |
| 1(b)(9): one surveyed small lot | One lot under five acres from the historical larger tract, with the required survey | The same exception can be used for each later lot |
For 1(b)(9), use the larger tract's dimensions and configuration on October 1, 1973. The provision excludes subsequent lots from that same tract and expressly preserves local requirements. Selling one lot at a time is not a way to reset it.
Other listed exceptions concern specified utility conveyances, public-purpose conveyances, correction of prior descriptions and wind-energy plats. Their conditions differ. Read the relevant paragraph. The no-new-access condition appears in specified exceptions, not every one.
A new access easement defeats 1(b)(1). That fact alone does not prove the under-five-acre trigger in 1(a), defeat every other exception or establish local approval. Section 1 also preserves specified county powers to adjust or supplement its requirements. Check the governing local rules for the actual land.
An exempt parcel can still have a recording duty. Under 1(c), if an Illinois registered surveyor makes a plat of a parcel otherwise exempt under 1(b), that plat must be recorded. This is not a statement that every property-related drawing is a subdivision plat.
Worked example: two small parcels and a large remainder
Marisol proposes three parts from twelve acres
Her proposal is three acres, three acres and a six-acre remainder. Assume no statutory exception applies.
Three plus three plus six is twelve. There are at least two parts, and some are under five acres. On the stated assumptions, 1(a) requires the survey and subdivision plat. The six-acre remainder does not change that answer.
Change the fact: only one small lot will be sold. That changes which exceptions might fit; it does not prove the tract's historical configuration, prior use of 1(b)(9) or compliance with local requirements.
Recording, dedication and vacation do different jobs
Recording. Section 2 addresses the completed plat, surveyor's statement, owner's acknowledgment, applicable approvals and county recording or filing. It also assigns changes to an unrecorded plat to the surveyor who prepared it, with a stated substitute-surveyor condition for death, incapacity or absence. The broker should not edit the lines personally.
Dedication. Section 3 gives acknowledgment and recording or filing conveyance consequences for portions marked as donated or granted, for the designated purposes. It also addresses municipal public-use areas held in trust. This does not mean that recording a subdivision transfers every private lot to the public.
Vacation. Section 6 provides a formal written, approved and recorded process for vacating a plat. After lots have been sold, all lot owners must join in the writing. Its required reservations for existing public-service facilities and its safeguards for public rights still matter. Redrawing the map or obtaining one owner's signature is not that process.
What should a broker refer to a surveyor?
225 ILCS 330/5 includes establishing or retracing boundaries, platting subdivisions and preparing descriptions that determine title or property rights within professional land-surveying practice. A real estate broker license does not confer that surveying authority.
Obtain the existing documents, identify the mismatch and refer it. Distinguish using an existing recorded description from creating or changing a boundary description. If the proposal keeps a shed with the seller by moving the line, the changed line needs the appropriate surveying, title and local review.
68 Ill. Admin. Code 1270.56(b), (d) and (e) distinguishes boundary surveys, subdivision surveys and mortgage inspections. A mortgage inspection does not constitute a boundary survey. Do not use it to promise a settled fence line or assume a subdivision approval merely because a document was prepared by a surveyor.
Try six original legal-description and Plat Act questions
Choose before opening the explanation. These study examples are not released or recalled PSI questions.
1. The deed points to a recorded subdivision
It identifies Lot 8, Block 2, Prairie View Subdivision and the recorded plat. Which method is being used?
- A street-address locator only
- A sequence of metes-and-bounds perimeter calls
- Lot and block
- A quarter-section description
Show answer 1
C is correct. A omits the plat reference. B would trace the perimeter through calls. C identifies the recorded-lot method. D would use section and survey-system references.
Change the fact: the wording instead follows boundary directions and distances from a point of beginning. That is a metes-and-bounds recognition clue.
2. A quarter of a quarter
Assume a standard 640-acre section. How many acres are in the NE quarter of its SW quarter?
- 160
- 40
- 320
- 10
Show answer 2
B is correct. A takes only one quarter. B uses 640 × 1/4 × 1/4. C takes half the section. D takes a further quarter that was not stated.
Change the fact: ask for the east half of that same NE quarter of the SW quarter. The study acreage becomes 20. The actual record still controls a real parcel.
3. Two small parts and one large remainder
An owner divides twelve acres into three, three and six acres. Assume no exception applies. What is the best answer under 1(a)?
- The stated division requires the survey and subdivision plat
- The six-acre remainder exempts all three parts
- The rule applies only when every part is under five acres
- A broker's listing sketch replaces the required work
Show answer 3
A is correct. A applies the any-part test. B and C replace it with a different acreage rule. D substitutes a marketing sketch for the statutory process.
Change the fact: two six-acre parts with no new street or access easement have no under-five-acre resulting part and fit 1(b)(1)'s stated size and access conditions. Local requirements remain separate.
4. Exactly five acres, plus a new access easement
A ten-acre tract is divided into two five-acre parts with a new access easement. Which conclusion is most accurate?
- 1(b)(1) applies because size is its only condition
- The easement alone proves a part is under five acres
- The proposal is automatically approved locally
- 1(b)(1) is unavailable; the underlying trigger and other requirements still need their own analysis
Show answer 4
D is correct. A drops the access condition. B changes the given acreage. C invents approval. D separates failure of an exception from proof of a statutory trigger.
Change the fact: remove the new access easement and assume no new street. The stated 1(b)(1) size and access conditions fit; that still does not settle every local requirement.
5. The same small-lot exception is claimed again
A qualifying first sale already used 1(b)(9) for a lot from a larger tract, measured by its October 1, 1973 configuration. Can a subsequent lot from that same tract use 1(b)(9) again?
- Yes, whenever the buyer changes
- Yes, if each sale has a separate closing
- No; that paragraph excludes subsequent lots from the same historical tract
- Yes, because a survey waives every local requirement
Show answer 5
C is correct. A and B invent reset conditions. C preserves the historical-tract limitation. D ignores the express local-requirements qualification. Another exception, if claimed, needs its own facts.
Change the fact: the proposed sale concerns a genuinely different historical tract. Investigate that tract's facts; a different label on today's tax map alone does not prove the exception.
6. The lender's document is called a mortgage inspection
A buyer asks whether that document settles a disputed fence boundary. Which response fits Illinois rule 1270.56(e)?
- Every surveyor-prepared document is a boundary survey
- A mortgage inspection is not a boundary survey; refer the boundary question for appropriate review
- The fence always controls the deed
- The broker may redraw the legal line
Show answer 6
B is correct. A overlooks the different services. B follows the rule's distinction. C assumes a boundary-law result without the evidence. D invents surveying authority.
Change the fact: a boundary survey is supplied. Read its actual findings and qualifications; do not turn its existence into a guarantee that every title dispute or proposed split is resolved.
Legal-description and Plat Act questions answered
Does every Illinois parcel under five acres need a new subdivision plat?
No. Section 1(a) addresses an owner's division into two or more parts when any resulting part is under five acres, subject to the exceptions. The mere existence or resale of an already established small lot does not establish that trigger. A proposed split, the tract's history, a specific exception and local rules require separate review.
Is a plat of survey the same as an approved subdivision plat?
No. A boundary survey addresses the property's boundaries. A subdivision survey creates new parcels and follows the applicable subdivision process. Illinois rule 1270.56 also distinguishes a mortgage inspection from a boundary survey. Read the document's actual purpose and status; a drawing or document title alone does not establish every required approval.
May a broker use an address or PIN instead of resolving a boundary mismatch?
An address or property identification number helps find the records. It does not resolve conflicting boundary calls or prove where a fence belongs. Obtain the relevant deed, recorded plat and survey, preserve the discrepancy and refer boundary work to the appropriate surveyor. Title and legal-interpretation questions need the appropriate legal review. Do not redraw the line to make the listing fit.
Connect the method to the exam question
The June 24, 2026 PSI outline, national I.B and Illinois III.E, covers the three description methods and the Legal Description/Plat Act topic. National Property Ownership is 10% of the broker national portion. Additional Illinois Laws and Regulations is 25%, or 10 of 40 scored state broker questions. These are whole-area allocations, not fixed counts for legal descriptions or the Plat Act alone.
Continue with the Illinois laws and regulations guide for related state topics. For more practice recognizing description methods and exception conditions, you can download Pass Illinois for additional broker-exam preparation.