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Costilla County Assessor

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Thomas Aragon

County Assessor

P.O. Box 344

San Luis, CO 81152

Phone: (719) 937-7670

eFax: (888) 709-5722

Email: assessor@costillacounty.net


Office Hours:

Monday - Thursday: 7:00 a.m. - 5:30 p.m.

No closure for lunch.




About Our Office

This office is directly responsible for discovering, locating, classifying and valuing properties. It is the responsibility of this office to update and maintain accurate property records. These records include improvements and all improvement characteristics, along with pictures of these improvements. Records also include land size, location, maps and transfer history.



Thomas Aragon - Assessor

Ronda Lobato - Deputy Assessor/Chief Appraiser

Pamela Vigil - Office Manager

Steve Valdez - Transfer Clerk

Loryn DeLeon - Field Inspector

Angelica Valdez - Field Inspector 

Benita Martinez - Administrative Assistant


2023-2024 Reappraisal Information

2023 Reassessment Explained

Protest Information

Protest Form

Notice of Valuation Form

Sales Gathering Period Timeline

Residential Sales Book

Reappraisal Reduction Information for 2023 taxes

Time Trend Explained

2023 Vacant Land Sales Book with Time Trend

Vacant Land with Well Sales

2023 Agricultural Land Appraisal

Video on Colorado appraisal - https://youtu.be/zOfFnn_AJVE

Colorado Map on percentages of increase in each county- https://gis.dola.colorado.gov/Residential_Value_Change/


2021-2022 Reappraisal Information

Protest Information

Residential Sales Book

Sales Gathering Periods Explanation

Study Period Graph 2021

Vacant Land Sales Book

Agricultural Land Valuation

Agricultural Land Valuation Summary

Why Adjust for Time or Market Condition Changes

Forbes Wagon Creek Residential Sales

2019-2020 Reappraisal Information

Helpful Information

Mass Appraisal Explained

New Ag Values Per Acre

Residential Sales Reappraisal 2019

Sales Gathering Periods Explanation

Vacant Land Sales Reappraisal 2019

2023 Costilla County Property Assessment Study - A Procedural and Statistical Audit


Abstract Brochures

2023 Abstract Brochure

2022 Abstract Brochure

2021 Abstract Brochure

2020 Abstract Brochure

2019 Abstract Brochure

2018 Abstract Brochure

2017 Abstract Brochure

2016 Abstract Brochure

Classification and Valuation of Agricultural Property

Understanding Property Taxes in Colorado

Property Valuation and Taxation for Business and Industry

Rebates, Exemptions, and Deferrals for Senior Citizens, Persons with Disabilities and Active Members of the National Guard or Reserves

Manufactured Homes

Natural Disaster Valuation in Colorado



Address Change Form (Download and save form to enter your information)

Petition for Abatement or Refund of Taxes (One Year Form)

Petition for Abatement or Refund of Taxes (Two Year Form)

Real Property Transfer Declaration (TD-1000)_Revised 1-16-21


Veteran with a Disability Application Instructions 2024

Veteran with a Disability Property Tax Exemption Application 2024

Veteran with a Disability Surviving Spouse Application 2024

Gold Star Spouse Instructions 2024

Gold Star Spouse Application 2024

Senior Citizen Long Form Application 2024

Senior Citizen Long Form Instructions 2024

Senior Citizen Short Form Application 2024

Senior Citizen Short Form Instructions 2024

Helpful Links

Department of Local Affairs

Colorado Assessors' Association

Click here to go to the "Assessor's Helpful Information" page