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Updated 2025 Tax Year

Union County
Property Tax Guide

Everything you need to know about property taxes in Union County, NM. Rates, due dates, exemptions, and how it affects your monthly payment.

10 Official Sources
8 min read
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Quick Facts
Tax Rate
3.0287% for residential properties (varies by special taxing district location)
Exemptions
4+ Available
Section 1

How Property Tax Works

Union County property taxes fund essential local services including schools, county government operations, fire protection, and various special districts. The property tax system operates on an assessment-based model where your home's assessed value is multiplied by the applicable tax rate to determine your annual tax obligation.

For the 2025 tax year, Union County's composite property tax rate is 3.0287% for residential properties, though your actual rate may vary depending on your specific location within the county due to different special taxing districts. Property owners should note that New Mexico assesses residential property at one-third of market value, so a $300,000 home would have an assessed value of approximately $100,000 before any applicable tax credits.

Section 2

What Makes Up Your Tax Bill

ComponentRateDescription
County GeneralVariesBasic county services and operations
School DistrictVariesLocal school district funding
Special DistrictsVariesFire protection, hospital, other local services
Total Composite Rate (FY 2025)3.0287%Combined rate for residential properties

Note: Actual rates vary by location within Union County based on which special taxing districts serve your property. Non-residential properties may have different rates. Contact the Union County Assessor for your specific district breakdown.

Section 3

When Are Property Taxes Due?

For the 2025/2026 tax year in Union County, property taxes are due in two installments:

Pro tip: If you pay through mortgage escrow, your lender splits these payments across your monthly mortgage. If you pay directly, set calendar reminders to avoid late penalties.
Section 4

Supplemental Tax Bills

Supplemental taxes are additional property tax bills issued when there is a change in property ownership, new construction, or improvements that increase the assessed value mid-tax year. These taxes cover the difference between what was originally assessed and the new assessed value, prorated for the remaining portion of the tax year.

For example, if you purchase a home in Union County in March that was previously assessed at $80,000 but now has a market value requiring a $120,000 assessment, you would receive a supplemental tax bill for the increased assessment amount multiplied by the applicable tax rate, covering April through the end of the tax year.

Example Calculation

Example 1: $300,000 Home

  • Market Value: $300,000
  • Assessed Value (33.33%): $100,000
  • Less: Head of Household Credit: -$2,000 (if applicable, requires application)
  • Net Taxable Value: $98,000
  • Annual Tax (3.0287%): $2,968
  • Monthly Escrow: $247

Example 2: $600,000 Home

  • Market Value: $600,000
  • Assessed Value (33.33%): $200,000
  • Less: Head of Household Credit: -$2,000 (if applicable, requires application)
  • Net Taxable Value: $198,000
  • Annual Tax (3.0287%): $5,997
  • Monthly Escrow: $500

Example 3: $1,000,000 Home

  • Market Value: $1,000,000
  • Assessed Value (33.33%): $333,333
  • Less: Head of Household Credit: -$2,000 (if applicable, requires application)
  • Net Taxable Value: $331,333
  • Annual Tax (3.0287%): $10,034
  • Monthly Escrow: $836

Note: Tax credits require separate applications and are not automatically applied.

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Section 5

Escrow & Property Taxes

Most mortgage lenders require property tax escrow accounts, collecting monthly payments along with your mortgage payment to ensure taxes are paid on time. Your lender will analyze your annual tax bill and divide it by 12 months, often maintaining a cushion of 1-2 months of payments.

Property tax bills are mailed by November 1st each year, and lenders typically pay the first installment by the December 10th deadline and the second installment by the May 10th deadline. You should verify that your lender receives and pays your tax bills correctly, as you remain ultimately responsible for timely payment even when using an escrow account.

How HonestCasa Helps
  • Understand whether your escrow is set correctly
  • See how rising taxes will change your monthly payment
  • Plan ahead instead of being surprised by "shortage" letters
Section 6

Frequently Asked Questions

Q: When are property taxes due in Union County for the current tax year? A: The first installment is due November 10th, with a grace period until December 10th. The second installment is due April 10th of the following year, with a grace period until May 10th.

Q: What tax credits are available and how do I apply? A: The primary credit is the Head of Household credit providing a $2,000 reduction in assessed value for qualifying residents. This requires a separate application to the County Assessor's office and is not automatically applied.

Q: Does New Mexico have a homestead credit that caps assessment increases? A: New Mexico does not have a homestead credit that caps annual assessment increases like some other states. Property assessments can increase based on market value changes without statutory limitations.

Q: How often are properties reassessed in Union County? A: New Mexico requires annual reassessment of all property, though significant changes typically occur during periodic revaluation cycles or when properties are sold or improved.

Q: What are the penalties for late property tax payments? A: Interest and penalties accrue on unpaid taxes after the grace periods (December 10th for first installment, May 10th for second installment). Contact the Union County Treasurer for current penalty rates.

Q: Can I pay my property taxes online? A: Check with the Union County Treasurer's office for available online payment options and accepted payment methods.

Q: How do special district taxes affect my bill? A: Your location determines which special districts (fire, hospital, etc.) serve your property. Each district adds to your total tax rate, which is why rates vary within the county.

Q: How do I appeal my property assessment? A: Assessment appeals must be filed with the County Assessor within 30 days of receiving your Notice of Value, typically issued by May 1st each year.

Verified Sources

Backed by 10 Official Government Sources

Every fact in this guide is sourced from official county, state, and federal documents.

01
County
County Net Taxable Valuesnmdfa.state.nm.us
02
Tax Doc
Certificates of Property Tax Ratesnmdfa.state.nm.us
03
Tax Doc
Tax Ratesdonaana.gov
04
IMPORTANT DATEStax.newmexico.gov
05
County
Assessors Office - Union Countyunionnm.us
06
Tax Doc
Delinquent Property Tax Auctions : Businessestax.newmexico.gov
07
Tax Doc
Property Taxes in New Mexiconmlegis.gov
08
County
For New Homeowners - Assessor - Bernalillo Countybernco.gov
09
Tax Doc
Property Tax Division : Taxation and Revenue New Mexicotax.newmexico.gov
10
relating to general obligation bondsnmlegis.gov
All sources verified as of 2025 Tax Year

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