Blog · September 30, 2026
What Is a Certified Survey Map?
A certified survey map, the CSM used in Wisconsin and similarly named maps in a few other places, is a recorded survey map that can divide land under that state’s rules. It is a real recorded map. It is not a nickname for every survey sketch, and it is not the county tax map.
Platbookmapper is an Amazon Associate. If you buy through an Amazon link on this page, we earn a commission. The link is a product, not the county map.
A defined instrument
In Wisconsin, a certified survey map is a particular recorded map, prepared by a surveyor, used for certain land divisions that are not full subdivisions, with a statutory form, owner’s certificate, and approvals the statute and the local ordinance require. Other states use different names for small divisions, such as minor plats or exempt splits, and some use certificate of survey for a different purpose. If your document does not say certified survey map and you are not in a state that creates them, do not borrow the label. If it does, the CSM is part of the chain. Deeds should cite the CSM by volume and page or document number, and the lot or outlot as the CSM numbers them. Reading the deed without the CSM is the same mistake as reading a lot deed without the subdivision plat.
What is on the sheet
Expect a location, a legal description of the parent, the new parcels with bearings and distances, monuments, a surveyor’s certificate, an owner’s certificate, and approvals or a note about them. Easements and restrictions may be on the face. The area of each parcel is given. More or less still means area is not the boundary. Because a CSM creates parcels simultaneously, the new parcels are not senior and junior to each other. They are children of the same map. A later deed that tries to reslice a CSM parcel by a kitchen-table metes description may create a tax split the local ordinance does not recognize. The assessor might still map it. Assessment is not approval. County GIS will often show CSM parcels because the assessor adopted them. The GIS line remains a tax line. The CSM image is the recorded map.
How Platbookmapper fits
The directory links you to the county GIS page, where the parcel id and sometimes the CSM number are visible. It does not store the CSM, draw its courses, show zip codes, or cover maps outside the United States. Order the CSM from the register of deeds citation. Check for later affidavits or amended maps. Do not measure the CSM off the screen with a phone and order a fence. A phone GPS, a wheel, and a laser measure are not surveys. If a corner monument is missing, a surveyor replaces it from the CSM and the remaining evidence, which is a different act from viewing the PDF.
What to do next
- Confirm the document is actually titled as a certified survey map.
- Cite the volume and page or document number in any note you keep.
- Read the certificates, not only the picture.
- Treat the parcels on one CSM as created together.
The mix-up to avoid
Calling every survey PDF a CSM. The name is a legal form in a specific system. A mortgage sketch or a record of survey is a different document with a different effect.
Questions people ask
Does a CSM always create four or fewer lots?
The number is a matter of the statute and the local ordinance at the time, and it has changed. Read the map and the ordinance context. Do not assume a lot count from a guidebook.
Is an outlot on a CSM a buildable lot?
Not by the name alone. Outlots are often reserved for stormwater, access, or future use, and the notes say so. Read the note before you treat Outlot 1 as a house parcel.
Find the county map
Search the county on the Platbookmapper home page. The directory links to the official parcel viewer. It does not draw the lots, and the line on the screen is an assessment map, not a survey.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.