The Geographic Service Area File


Table of Contents


This sheet contains the following sections

  • Geo File Names
  • Sheets
  • Overview of Fields
  • Fields, Main Sheet
  • Fields, Check Sheet
  • Plan Types
  • Competition Macro
  • Changes in the GSA
  • Contact
  • 2006 Rx Enrollment Data

Please feel free to use your browser find function (Main Menu ===> Edit ===> Find) to jump to any section.


Geo File Names


The Geographic service area file is known as the

  • The Geo file
  • GSA
  • Geographic Service Area file
  • Service Area file.

It has been published monthly since June 2001 with the exception of Sept 2001 and February 2005.




The Geo file has two sheets

  • The main sheet---the main sheet has the name form Geo-MMYY where MM and YY refer to the month and year. For example Geo-1205 is the name of the main sheet in the Dec 2005 geo file.
  • The Check sheet.


Overview of Fields


Prior to presenting the fields of the Geo file we present a high level overview. Suppose by way of example a fictitious Medicare Advantage Organization (MAO), called the Cheerful Health Company contracts with CMS to provide services in Kings and Queen county NY. Suppose further that a NY resident moves to Baltimore and joins the Move Here MAO in Baltimore Maryland. Move Here must legally provide services to this person even though his official residence is in NY (This situation will remain for a short while till Social Security is informed of the change). We can say the following about this situation.

  • OOA -- the NY Person who moved to Baltimore is called an Out of Area enrollee (OOA) for the Move Here MAO in Md.
  • Main Sheet Records--The Cheerful company will have two records in the Geo file--one for Kings and one for Queens. The Move Here company will have one record in the Geo for Baltimore.
  • Record enrollment--The Kings record for Cheerful will list the aggregate enrollment for Cheerful in Kings county (This of course will be distinct from the aggregate enrollment for either Kings county or for Cheerful)
  • Total Enrollment --The total enrollment field for Move Here will include the resident from NY. The Total Enrollment field is not on the Main sheet but on the Check sheet.
  • In Service Area Enrollment (SA Enrollment)--The SA enrollment for Move Here will not include the resident from NY
  • OOA Enrollment - Note that neither of the 3 records on the Main sheet will include the ooa enrollee from NY. In other words the ooa enrollment is lost from the Main sheet records. (However the ooa enrollee is included in the total enrollment field of the Move Here organization).
  • Under 11 Records--The Move Here enrollment for Baltimore will be included in the Main sheet. If that enrollment is between 1-10 then the record will be there but with blank enrollment. In other words the true number of enrollees is omitted (but the record is kept) if the true enrollment is between 1 and 10. The reason for this omission is the CMS interpretation of the privacy rules of the HIPPA act.
  • Three views of Move Here?s enrollment---We can obtain enrollment for Move Here in three ways--(a) By reviewing the Total Enrollment field on the Check sheet, (b) By Reviewing the In Service Area enrollment field on the Check Sheet, (c) by summing all records in the Main sheet with the Move Here MAO.
  • Typical Differences between the Three views---In our example the difference, for Cheerful, between the Total and In Service Area enrollment will be 1. Typically this difference for risk plans is below 1% (It may be higher for non risk plans). Theoretically the sum of records, with a given MAO, on the main sheet should equal the in service area enrollment on the check sheet--however differences may arise from the under 11 records. Typically these differences will be 1/4-1/2%.
  • Remedies for the Missing Records---The In Service Area enrollment on the check sheet represents the aggregate enrollment for Move Here. If this number is bigger than the sum of records on the Main sheet for Move Here then we can go back and distribute the average difference per blank record over the blank records. This is a useful, but not an exact approximation.


Fields of the Main Sheet


  • H### -- This is the CMS contract number. Most Contract numbers begin with H and are followed by 4 digits. The 1st and 2nd digit are typically (but not always) the social security state code. Be aware that even pre 2006 some H## do not begin with H (e.g the H## may be a 5 digit number)
  • OrgName-- Many Organizations use similar names for their contract name and their marketing name. When there is a conflict we use the contract name.
  • Type-- Currently there are 10 plan types (For example Risk, PPO, Cost). Please see the Type subsection of this document for a list.
  • StName--Recall from the overview subsection of this document that the geo report presents MAO enrollment for each state-county unit. The StName field contains the English 2 letter abbreviation of the state. The County field contains the full English name of the county. The State County Code field contains the Social Security 5 character code for the state and county. Users should be aware of two things: (1st) It is good database practice to include state county codes, the reason being, that sc codes are unambiguous while names are ambiguous. For example the following three names refer to the same county--"Saint Louis", "St. Louis", "St Louis". An improperly set up database would lose information if only English names were used. (2nd) Those who wish to merge the Geo file with other files (like Census data) which use the FIPS 5 character state county code will need a FIPS-SS crosswalk. Such crosswalks are available on both the CMS and external websites.
  • County --- See the description of the StName field.
  • Partial? --- When an MAO contracts with CMS to furnish services it normally does so for a collection of counties (possibly one). Under limited circumstances and with the approval of CMS an MAO may contract to provide services for only part of a county (one important factor for allowing this is evidence of non discrimination in selecting this partial county). In the event a county in a service area of an MAO is a partial county the Partial? field has a P- entry. Otherwise the field is blank. The Zips in the partial county that is serviced are listed starting in the Zips column. In the event that there are more than 240 zips (more than an excel or access sheet can hold) then the All zips? field will have the entry NOT all zips (Otherwise it will be blank).
  • All zips? --- See the explanation of the Partial? field above.
  • # States --- Typically a plan contracts with a state to offer insurance within that state. However some plans may be multi-state or national. This is very common with PFFS plans. In such a case the #states field lists the number of states in which the service area of the MAO lies. Note: Please see the description of the enrollee field below: A very small number of records--- typically less then 10 in 10000 records have the county entry marked undefined. This typically happens with a national plan which services many states. However if the county entry is marked undefined then the # states field will have a one. However most national PFFS plans have all their counties listed and the # States field reflects the true number of states involved.
  • State  County Code --- See the description of the StName field.
  • Eligibles -- The eligible field contains the count of ever eligibles for the previous quarter. For example the May, June and July Geo will contain the March count of eligibles. The August, Sept, and October Geo will contain the June count of eligibles. The ever eligibles include all individuals who either currently or formerly were entitled/enrolled in either part A original Medicare, part B original Medicare or both. The ever eligibles also include the attainment file--those individuals who will attain their 65th birthday within 4-5 months. By law these individuals may enroll in original Medicare with a future effective date.
  • Enrollees --- This indicates the current enrollees (as of the 1st of the month) for the MAO of record and for the county of record. Numerical illustrations were provided in the Overview of fields subsection of this document. Important information on the enrollee field was provided there. The user should be aware that due to the source of data a very small number of fields have the county field marked undefined. This typically happens when the plan is a national plan (Such as for example a national PFFS plan). However the number of records with the undefined county is typically less than 10 (out of 10,000 records). Most National plans have all counties they service listed.
  • Employer Only County --- By law when an MAO offers a plan it must typically do so to all current eligibles in the service area of the MAO. However an MAO may, under limited circumstances and with the consent of CMS, have this requirement waived. The MAO may restrict enrollment to those individuals who belong (or are appropriately related) to an employer. If the only offerings by an MAO in a county are to employer only plans then a 1 appears in the Employer only county. Otherwise a 0 appears. An offering in a county to all eligibles is called a public offering.
  • Zips --- See the explanation of the Partial? field above.


Fields of the Check Sheet


The Check sheet currently has the following 6 fields

  • H### -- See the H### field description above for the main sheet
  • In Service Area enrollment--This is the aggregate enrollment of the MAO but only in those counties it is authorized to provide services in. For further details see the field overview subsection of this document.
  • Total Enrollment--This is the aggregate enrollment of the MAO. For comparisons of the three views on MAO enrollment see the field overview subsection of this document.
  • Percent of OOA(Out of area enrollees) -- This is the count of OOA enrollees divided by the in-service area enrollment(It conceptually represents how many extra enrollees there are besides the enrollees in the authorized service area). For typical ranges of the percent of ooa see the field overview subsection of this document.
  • Plan Type -- See the list of plan types in the type subsection of this sheet
  • Organization Name -- See the Organization name field description for the main sheet.




The current plan types include

  • RISK plans (Also known as Coordinate Care Plans, CCP, and Health Maintenance Organizations (HMO);
  • COST plans
  • HCPP plans
  • PACE plans (Program for the All Inclusive Care of the Elderly)
  • PFFS plans (Private Fee for Service Plans)
  • PPO (Preferred Provider organizations---these are paid like Risk plans)
  • PSO (Provider Sponsored Organization--there are also paid like Risk plans)
  • DEMO (Demonstration projects)
  • DEMP (PPO Demos, that is demonstration projects using the PPO model)
  • DEMC (Cost Demos, that is demonstration projects using a cost payment scheme)

An explanation of the characteristics of the various plan types may be found in chapter 1 of the Managed Care Manual. The Managed Care Manual may be found in the Regulations and Guidance bucket of the main CMS web page. Under this bucket one should click manuals and then click internet only manuals. The Medicare Advantage manual is publication 100-16.


Competition macro


Since September 2004, the geo file has a competition macro. The instructions for using this macro are on the cover sheet. The competition macro allows a user to select either

  • an organization, or
  • a group of counties, possibly in different states
and to obtain by plan or county
  • aggreagate MA enrollment
  • aggregate Eligibles and
  • Penetration.

The competition macro is particularly useful for identifying areas of high competition.


Changes in the Geo (READ ME File)


There have been many changes in the Geo file since its inception: Some examples of current features that were not in the original file are:

  • The competition macro
  • The Employer only field
  • The PPO Demo type (DEMP) (All demos were formerly lumped together)

The ReadMe.Txt file contains a chronological list of changes over the years. This file should be particularly useful to users studying trends over time who must know the correspondence between terms in the older and newer files.




For further information on the Geo file contact Russell Jay Hendel, at Russell.Hendel@Cms.HHS.Gov.


2006 Rx Enrollment Data


The CMS has published Rx, but not MA-only, enrollment data, aggregated by state, county and Medicare Advantage Organization (but not aggregated by H###). The Related Links Inside CMS section below contains links to these downloadable files.

These 2006 Rx enrollment files have a similar, but not identical, format, to the pre-2006 files. For example,

  • enrollment data is for Rx enrollment, but not for MA-only enrollment;
  • Aggregation is by Parent organization, not by H### or plan;
  • aggregation is reported separately in two files for PDP and MA-PD;
  • Organizations are identified by their English name not by numbers;
  • Enrollment numbers are rounded to the nearest 100, not given exactly;
  • Enrollment under 50 is excluded (vs. enrollment under 10 in the pre-2006 files);
  • Employer Group only plans are excluded;
  • Out of area enrollees are excluded (in both 2006 and pre 2006 files);
  • Various other issues affecting rounding and addresses.
Page Last Modified:
09/06/2023 04:57 PM