Do Tax Maps Create Titles? -- A Cautionary Tale for Land Surveyors.
Land use professionals are generally quick to argue against the accuracy of tax maps when they disagree with the information shown on the maps. However, there seems to be an unconscious desire among land use professionals to give validity to the lines drawn on these documents. Court records illustrate how often various parties attempt to use these regulatory tools for purposes that they were never intended to serve.
Recent court decisions from New York provide several relevant examples. In one case, a surveyor relied on tax maps provided by others in an attempt to locate a parcel of land. There was no apparent effort made to obtain previous descriptions of the disputed tract, or to perform a field survey of the land.
The problem arose (in part) as the result of a tax deed generated for the sale of 11 acres that had been foreclosed on by the county government. Since the deed referred only to the tax parcel for a description, it seemed to create a plausible excuse to use the tax map in order to determine the location of the parcel.
In this case, the result was not simply an erroneous location of a boundary line but rather a complete displacement of the 11-acre tract to a location where it had never existed. In a unanimous decision the judges dismissed the tax maps as insignificant for determination of title issues:
“In describing the disputed parcel's location as being within the plaintiff's property, the defendants' surveyor merely relied upon and replicated the tax map's erroneous estimation of the location of the disputed parcel, which was not sufficient to raise a triable issue of fact as to the parcel's true location…” 
The Missouri courts provide interesting commentary on the general unreliability of tax maps when used to prove the location of a disputed boundary line. In this instance, Clarida had no other evidence to prove his ownership of the 10-foot strip of land because it was not included within his deed description.
The local tax assessor was one of the individuals who testified in the case. While Mr. Clarida hoped the assessor’s statements would strengthen his claim, the testimony ultimately had the opposite effect. The assessor noted that the maps were accurate only down to a 50-foot range and did not clearly demonstrate who owned the disputed 10-foot strip. In addition, some lines were dashed rather than solid, indicating that the employee who drew them was unsure of the ownership of the land in question.
Considering the statements made by the assessor, the court expresses puzzlement as to the possible significance of the tax map in these circumstances:
“The assessor explained that a tax map is not intended to be used as a survey and should not be relied on as an exact placement of any structure in relation to any lot line. He further testified that there are occasionally errors on these types of drawings, and in fact, there was previously an error on a lot adjacent in the area in dispute.” 
A recent Tennessee decision found a surveyor charged for negligence when he based a retracement on a tax map and then subdivided the resulting tract. As a result of his work, several of the lots as marked actually overlapped with the adjoining tract. The court emphasized that by ignoring the latest recorded deed for the subject parcel, the work performed violated the Tennessee standards of practice for land surveying. The surveyor:
“…in derogation of the rules promulgated by the Tennessee State Board of Examiners for Land Surveyors, failed to create his survey using the latest recorded deed to the property and instead utilized a tax map provided by the Tax Assessor's office.” 
The court goes on to support a claim of negligence against the surveyor. He was ultimately held responsible for any damages that resulted from the negligence or lack of basic surveying skills on his part.
In an interesting Vermont case, a surveyor became involved in a development scheme that forced him to decide between following the clients’ wishes and performing a proper retracement prior to development of a parcel of land. The developer had initially used a tax map as the basis for a preliminary concept sketch to indicate the rough layout of the proposed division.
Unfortunately, an individual acting as an agent for the developers told the surveyor that re-surveying the outside boundaries of the parent tract was unnecessary. More significant to the ultimate outcome was the surveyor’s concession to this request. When all work was completed, a strip of land remained that was not intended by the original developer. Total damages awarded by the lower court totaled over 70,000 dollars.
While the background information included in this case documents numerous problems, the decision includes a warning for any surveyor considering tax maps as a reliable source of survey information. Among other undisputed findings, the court notes: “…(2) defendant knew that the preliminary sketch was based upon the Ferrisburgh tax map; (3) tax maps are not intended to be used in establishing the boundaries on any survey, and it would not be in accordance with professional surveying standards to do so; … defendant used the tax map to guess at the location of the southern boundary line of the property (and thus the subdivision).  As a general rule, any time a court concludes that guesswork has been used as the basis for professional opinions, the outcome will likely be a poor one for the guesser.
Additional findings in this case noted that physical features on the land should have alerted the surveyor to a discrepancy. Finally, the court observes that the surveyor made no mention on the face of his survey that the outside boundary lines had not been verified.
In a unanimous opinion, this court considered the evidence of negligence on the part of the surveyor so obvious that they saw no need for expert testimony to make the determination.
The Vermont court based its decision in part on their assessment of the validity of the tax maps and their relationship to the local standards of practice: “…the trial court also found that professional survey standards require that a survey must verify the perimeter boundaries of the parcel to be surveyed. Defendant contends that this finding cannot stand because plaintiffs failed to present expert testimony to support it. In response, plaintiffs point to testimony indicating that defendant was aware that preparing an accurate survey required researching the deeds of adjoining owners to verify the perimeter boundaries of the land to be surveyed.” 
Tax Maps in Adverse Possession claims
In a separate Tennessee ruling, a party claiming adverse possession insisted that a tax map could be considered a legitimate document to prove “assurance of title.” Some states do apply a relaxed standard for color documents, as compared to requirements for documents controlling legitimate title transfers. Because of this dual standard, this argument might seem reasonable in some jurisdictions.
As seen in the following quotation, the Tennessee court defines “assurance of title” using language substantially similar to the common definition of color of title:
“Assurance of title is "something in writing which at face value, professes to pass title but which does not do it, either for want of title in the person making it or from the defective mode of the conveyance that is used."”
In the court’s final assessment, Judge Clement was quick to dismiss tax maps in this context: “…tax maps cannot be used to establish boundary lines or assurance of title. … While it may place one tract of land inside the other, the tax map cannot be used to establish boundary lines or color of title. …Tax maps do not "on their face profess to pass title" and, thus, cannot be assurance of title.” 
Tax maps produced as evidence and the legitimacy of testimony by a tax appraiser were considered in a Georgia claim of adverse possession. Although the testimony was found to be legitimate for the limited purpose of determining acreage, Judge Hines notes that maps produced by outside sources could be considered hearsay evidence for purposes of determining title:
“The fact that the property lines and other information on the plats were generated by an outside source, and thus, constituted hearsay might well preclude the plats as presumptive evidence under O.C.G.A. § 36-7-12. However, the plats were not precluded as a basis of the appraiser's expert opinion because the presence of hearsay in such circumstance does not mandate exclusion but instead goes to the weight to be accorded the evidence. …” 
Court instructions to the jury included a strict caution that the tax maps be used only as evidence of county tax records. The jury was not permitted to use them as evidence of ownership.
The overall pattern is clear – tax maps are a regulatory tool and may be used to determine who pays taxes on a particular tract, but are not generally admissible for proving ownership of a given parcel.  Relying on these documents as a basis for a survey puts the professional on very shaky ground.
List of Sources:
1. Morganteen v. Brenner: 28 A.D.3d 725; 814 N.Y.S.2d 213; 2006
2. Blaylock v. Clarida: (Missouri) 987 S.W.2d 18 (1999)
3. Whitelaw v. Brooks: (Tennessee) 138 S.W.3d 890 (2003)
4. Bull v. Pinkham Engineering: 170 Vt. 450; 752 A.2d 26 (2000)
5. Summers v. Stubblefield: (Tennessee) No. M2014-00425-COA-R3-CV (2015)
6. Resseau v. Bland: 268 Ga. 634; 491 S.E.2d 809 (1997)
7. Conder v. Salyers: Tennessee 421 S.W.3d 589 (2013)