Tax Mapping: Instiute of Remote Sensing Anna University Guindy
Tax Mapping: Instiute of Remote Sensing Anna University Guindy
Tax Mapping: Instiute of Remote Sensing Anna University Guindy
CONTENTS
INTRODUCTION
Tax Map Preparation and Maintenance
Use of a Tax Map
INDEX SYSTEM
Types of Index Cards (Manual System)
Mechanized (Computer) Cross Reference Index File
Index Maps
MAINTENANCE SYSTEM
Maintenance System Description
Assessor's Part and Use of the Maintenance System
Selecting a System
Cost and Conversion Methods
Map Maintenance
REFERENCE
1. INTRODUCTION
This material has been prepared as a guide to local assessors in the use of a tax map. Definitions
of terms in tax mapping are included in the appendix.
A tax map is a special purpose map, accurately drawn to scale showing all the real property
parcels within a city, town or village. These maps are used to locate parcels and obtain other
information required in assessment work. As changes take place in ownership, size, or shape of
the parcels, the tax map system must be updated.
The initial preparation and continued maintenance of tax maps are the responsibility of
the Real Property Tax Service agency of the county or assessor where applicable. The
cooperation and assistance of assessors are essential in a successful Tax Mapping
Program.
Data which is obtained from state, federal, county and local government
departments must be located and analyzed for use in tax map preparation.
A base tax map is prepared using aerial photographs specifically created under
controlled conditions. The aerial photographs clearly show all geographical
features such as streets, roads, lakes, streams, railroad and utility lines, as well as
property occupancy lines when they are well defined on the ground. Points of
reference on the ground will have been prominently marked so as to provide
check points on the photography. This photography is used as the foundation for
preparing base manuscripts and includes features shown thereon that will assist
the plotting of parcels. The base manuscripts are the basic maps from which the
final tax map is prepared. All deeds or other instruments of conveyance are
examined to determine the ownership of each parcel to be plotted on the maps.
A tax map is generally drafted on map sheets 30 inches high by 42 inches wide.
The parcels are delineated on the tax map using the data obtained through deed
research and plotting. Every parcel on a tax map is assigned a parcel number and
a coordinate locator number. An index map is prepared showing the area covered
by the tax map in a city, town or village. When the tax map is completed, the map
sheets may be bound together in sets or otherwise filed by the city, town and
village. The original maps remain where the maintenance is to be done. Prints are
provided to the assessors. According to the State Board's Rules for the Preparation
and Maintenance of Tax Maps for Real Property Assessment and Taxation
Administration, the assessor's copies of the tax map are a public record and must
be displayed and made available for inspection by the public.
Once a tax map is completed, it must be kept up-to-date. Revisions are required
when there are changes in parcel size or shape. The same data and methods are
used during the maintenance process as were used in the original work.
The formation of new subdivisons generally requires the addition of many new
parcels to the tax map. If many new parcels are added, a new map sheet may have
to be prepared for that area.
A tax map is primarily used by local governments to maintain a current inventory of all
parcels in a city, town or village.
1. Property Identification
The size, shape and dimensions (or acreage) or a parcel may be found on a tax
map. Cross-reference through the parcel number to matching index cards or
computer listings provides still other parcel information. The parcel numbering
system provides a history of the way parcels are subdivided.
2. Assessment Purposes
A tax map reduces the amount of work involved in assessment. Parcels are
quickly located and additional information is easily obtained from the cross-
reference index file.
In a reassessment program, tax map parcels are easily grouped on the map for
delineation of valuation influences.
A tax map even simplifies the preparation of the assessment roll itself. Parcel
identification numbers on an approved tax map constituted a legal description of a
parcel on an assessment roll and are concise and accurate.
A county tax map covers all the cities, towns and villages in the county. Each set of maps for a
city, town and village is complete within itself. Each map sheet of a tax map covers one specific
area, called a section. Every section is assigned a section number. The index map shows, and
identifies, the areas covered by each of the section maps of that municipality.
Parcels delineated on a tax map are identified by numbering systems. These numbers constitute a
description for each parcel assessed and are used to locate the matching index file data for the
parcel. The index file contains important data about the parcel and references to still further
information.
Each map has a legend at the bottom of the sheet that explains many of the lines and
symbols used on the map. An explanation of some of these items follows:
Areas with many small parcels are generally plotted using a large scale, such as 1
inch equals 50 feet. Cities and villages are generally mapped at a scale not smaller
than 1 inch equals 100 feet. Where the area being mapped contains relatively few
small parcels, the scales used are generally 1 inch equals 200 feet or 1 equals 400
feet. Dimensions are given for each boundary of parcels of less that one acre.
These dimensions are obtained from property deeds and other records. If the data
are not available from these sources, the dimensions are scaled. In this case the
dimensions are labeled with an (s) after the dimension.
Parcels of one acre or more need show only the road frontage dimensions. The
parcel acreage must also be given. If the acreage is a calculated value, the acreage
figure is followed by a (c).
Lines and symbols are used on the tax map to indicate boundaries and other
distinguishing features. The legend shown on each map will explain the lines and
symbols being used. Depending on the mapper or local circumstances, other lines
and/or symbols may be employed.
Parcel numbers and coordinate locator numbers are required for every parcel of property.
1. Parcel Numbers
An individual parcel number is assigned to each parcel in the county when the
map is prepared.
The section numbers are based on county modular units. Generally, every
county is divided into modular units, 8,000 feet by 12,000 feet. The
12,000 foot dimensions lie along the north and south boundaries and the
8,000 foot dimensions lie along the east and west boundaries of these
modular units. These modular units correspond to a map scale of 1" = 400'
and will measure 20" x 30" on each section map.
Each of the modular units is assigned a section number. The numbers start
with one and increase consecutively from left to right across each row of
modular units in the county starting with the top row. You will note also
that certain modular units cross town and village lines. Modular unit
boundaries do not necessarily coincide with city, town and village
boundaries.
When a scale larger than 1" = 400' is required, the section number is
followed by a two-digit suffix number which indicates the scale and the
area within the modular unit that is mapped at the larger scale. (Refer to
Exhibits 3C and 3D in appendix). Exhibit 3C shows the area covered by
the modular unit at larger scales of 1" = 200', 1" = 100', and 1" = 50'.
Notice that at 1" = 200' it requires four sections to cover the same area
shown at 1" = 400' (at 1" = 100' it requires 16 sections, at 1" = 50' it
requires 64 sections). Exhibit 3D shows the actual suffix numbers to be
used with the 1" = 400' section number when larger scales of mapping are
used.
Typical section numbers for a county originally divided into 1" = 400'
modular units might look like the following:
When parcels are divided, now parcels are formed known as subdivisions.
The subdivisions carry the original lot or parcel number, and a suffix
starting with the number 1 is added. If part of the parcel, prior to
subdivision, has been retained by the original owner, it carries the suffix 1.
Where an original parcel is extensively altered, it will be necessary to
renumber the parcels. Refer to Exhibit #4 for an example.
The same general procedure applies to parcels that have been combined,
possibly with slight variations.
a. Origination
The first set of digits shows the final easterly reading. The second shows
the final northerly reading. See Exhibit #5.
The term coordinate locator number means an east reading and a north
reading, in feet or meters, taken from the point of origin of the appropriate
zone of the New York Coordinate System to the visual center of each land
parcel.
b. Subdivision
To obtain maximum benefit, a tax map must be used to the greatest extent
possible. When this is done, considerable time and effort in all phases of assessing
work will be saved. The assessor may wish to have copies of section maps
reduced in size for field use.
Knowing the location and shape of parcels is a great assistance during any
assessing program. Since parcels can be located rapidly from the maps,
and further data can be obtained from the associated index system, much
valuable time can be saved. The parcels to be assessed may be
conveniently grouped for efficient coverage.
3. Grievance Day
Part of the index system is an index map which shows the coverage of
each section map within a city, town or village.
INDEX SYSTEM
The index system consists of a series of cross-reference index data files and index maps for each
city, town and village. Both tools facilitate locating parcels on the section maps and refer to other
related parcel information.
In some jurisdictions, the cross-reference index data are still manually entered on cross-reference
index cards. In this type of setup, the index cards are generally maintained by each assessor and
County Real Property Tax Service Agency in two sets: usually one set is filed numerically by
parcel number and the other set is filed alphabetically by surname of the owner.
In a growing number of jurisdictions, the cross-reference index data are captured on IBM cards,
magnetic tape or disc, and maintained by the County Real Property Tax Service Office.
Computer printouts are supplied to the individual local assessors for their day-to-day use and
maintenance. New copies of the computer printouts are supplied periodically as required.
The index maps serve as a key to locate the various section maps in a municipality.
In some index card systems there are two identical sets: one filed by parcel number and
the other by owner's surname.
Other systems use the numerical set as the master cards, containing all information. In
such a system, the alphabetical cards merely refer to the matching card by parcel number.
Minimum State Board requirements for index cards are given below.
1. Numerical
2. Alphabetical
Where the alphabetical set of index cards is not a duplicate of the numerical set, a
single card may be used to list all properties owned by a single owner. In this
case, the following information must be provided.
a.
Owner's name, with the surname being the prominent feature for filing.
b.
The complete mailing address of the owner.
c.
The name of the city, town or village.
d.
Property address.
e.
Parcel number.
f.
Deed reference - Liber and page.
g.
When the property is sold, there should be room provided on the card to
indicate the new owner, the date sold, and the new deed reference.
B. Mechanized (Computer) Cross Reference Index File
In this type of arrangement, all the minimum State Board requirements for the numerical
data are captured and stored in a master computer file. A printout can then be produced
automatically, based on either a numerical or alphabetical sequence, because the
numerical file duplicates all the information on the alphabetical file. An alphabetical
listing, therefore, would list any and all parcels owned by any taxpayer in sequence
according to surname, with all the data pertinent thereto.
C. Index Maps
The index maps for a municipality are at a smaller scale than the individual section maps.
On each index map is found the outline of each section map in the municipality with its
proper numerical designation. To assist in locating a particular section map, features such
as major roads, streets, waterways and railroads are shown.
MAINTENANCE SYSTEM
Continued maintenance of the tax map and index system is necessary to keep both sets of records
up-to-date. Without continued maintenance, the tax map and index system will rapidly become
useless. County tax map systems approved by the State Board are required by statute to be
maintained by the county. Prior to completion of a tax map project, the county director of real
property tax services will provide assessors will explicit information as to how the tax map
maintenance system will operate in their county. The following description is general in nature,
pending issuance of specific instructions by the county director of real property tax services.
As changes occur in parcel size, shape or number, revision to the tax map and index file becomes
necessary. The actual maintenance work is the responsibility of the county, except in a few
designated counties where it is the specific responsibility of the individual assessors.
The assessors' cooperation and assistance are essential in the maintenance of the tax map as well
as in the initial preparation of the tax map.
All tax map revisions and additions require changes to be made in the index system, but
not all changes in the index system require tax map revisions.
a. Parcel Number
Parcel numbers are changed whenever parcels are split or new parcels
established. It is sometimes necessary to renumber all the parcels in the
whole book.
c. Acreage calculations
d. Subdivisions
With the addition of many new parcels, it may become necessary to make
new larger scale maps. When this is done, new section numbers are
generated. All parcels covered by the old maps then receive the new
appropriate section number as part of their parcel number.
2. Index System Maintenance
a. Revisions
Index file revisions are required when any of the data included on the file
become obsolete. This usually occurs whenever any changes are made in
the tax map. The index file data for the affected parcels are then revised.
New file data must be added to the index file system when new parcels are
created.
After the tax map and index file are completed for a city, town or village, copies of the
tax map and index file will be provided by the county to the local assessor. Revised tax
maps or pertinent portions thereof will be furnished by the county to the assessor each
year.
1. Recording Changes
Information such as ownership changes and the creation of new parcels will
require action by the county tax map maintenance department. These changes will
be forwarded to the assessors and they will have to keep their record's current
according to the established maintenance system.
Changes or corrections may occur that may come to the attention of the assessor
in the first instance. In such cases, the assessor must notify the county tax map
department of such changes.
Tax Maps have become a significant tool for municipalities in New York State. The process of
converting the traditional paper tax map to a computerized (automated) tax map is known as a
digital conversion. The digital data (maps) have become an important commodity for land-
related and Geographic Information Systems (GIS) adopted by many county govenments as an
approach for gathering, storing and managing such data. Digital (automated) mapping systems
facilitate the planning and analysis of a wide variety of data, from emergency response to land
valuation. If standardized, the data can be readily exchanged with other departments and systems
throughout the municipality and further shared with other governmental agencies outside the
municipality. A digital tax map, when linked with the assessment data, can be a great asset to the
assessor for establishing property market value.
A. Selecting a System
Adequate time and resources should be allocated to planning, designing, and selecting a
system. All potential users should be identified and their needs addressed when choosing
or designing a system. It is also important to consider whether the system will be required
to communicate with other departments containing land-related or spatial data. A systems
analyst or tax map specialist can be helpful in this regard.
A fully automated system that supports interaction between graphics and text information
is preferable to a computer-assisted drafting (CAD) system. Computerization of the map
data provides the capability to manage, analyze, summarize, and display geographically
referenced information (GIS). The GIS facilitates the sharing of data, allowing various
users to manipulate and selectively retrieve "layers" of parcel information and to produce
composite maps with only the data needed by each. It also eliminates the duplication of
effort inherent in separate map systems.
The two primary methods of converting tax maps to a digital format are scanning and
manual digitizing:
Digital tax maps should be continually maintained by qualified technicians. Digital maps
represent a substantial capital investment, which is lost unless all changes and corrections
are made on a current basis. Map maintenance involves recording description changes,
parcel corrections from new and more accurate survey data, and most importantly
notifying tax map users and assessors of these changes. For digital or computerized map
data a backup procedure should be in place in case of computer failures.
REFERENCES
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