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Updated 2025 Tax Year

Union County
Property Tax Guide

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

5 Official Sources
8 min read
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Quick Facts
Tax Rate
Approximately 1% of market value (varies by taxing district - school, township, county)
1st Due
May 30
2nd Due
Oct 31
Exemptions
4+ Available
Section 1

How Property Tax Works

Union County, South Dakota operates under the state's property tax system to fund essential local services including schools, roads, law enforcement, and county operations. Property taxes in Union County are calculated based on assessed values determined by the county assessor, with tax rates that vary by location within the county depending on the specific taxing districts that serve each property.

The effective tax rate in Union County typically ranges around South Dakota's statewide average of approximately 1% of market value, though actual rates can vary significantly based on your property's location within various special taxing districts such as school districts, townships, and other local service areas. Property owners should note that South Dakota does not impose a statewide assessment cap, allowing local jurisdictions flexibility in setting tax rates based on budget needs and community priorities.

Section 2

What Makes Up Your Tax Bill

ComponentRate RangeDescription
County General0.2% - 0.4%Basic county services, administration, law enforcement
School Districts0.4% - 0.8%Local school operations and facilities
Township/Municipality0.1% - 0.3%Local municipal services where applicable
Special DistrictsVariesFire districts, library districts, other special services
Total Effective Rate~1.0%Combined rate varies by specific location

Note: These rates apply to the current tax levy year and represent typical ranges. Your actual tax rate depends on the specific combination of taxing districts serving your property. Contact the Union County Assessor's office for precise rates applicable to your property location.

Section 3

When Are Property Taxes Due?

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

First Installment
May 30
Delinquent after Dec 10
Second Installment
Oct 31
Delinquent after Apr 10
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 property taxes in Union County are triggered by specific events that change a property's assessed value during the tax year, primarily ownership changes and new construction or improvements. When these events occur, the county assessor determines the difference between the old and new assessed values and applies the current tax rate to calculate the supplemental tax amount.

For example, if you purchase a home in Union County that was previously assessed at $200,000 but now has a market value of $300,000, a supplemental tax would be calculated on the $100,000 difference in assessed value. The supplemental tax would be prorated based on the number of months remaining in the current tax year, ensuring you pay taxes based on the current assessed value for the period you own the property.

Example Calculation

Example 1: $300,000 Home

  • Market Value: $300,000
  • Assessed Value: $300,000
  • Less: Homestead Tax Credit (if applied): -$4,000
  • Net Taxable Value: $296,000
  • Annual Tax (1.0% rate): $2,960
  • Monthly Escrow: $247

Example 2: $600,000 Home

  • Market Value: $600,000
  • Assessed Value: $600,000
  • Less: Homestead Tax Credit (if applied): -$4,000
  • Net Taxable Value: $596,000
  • Annual Tax (1.0% rate): $5,960
  • Monthly Escrow: $497

Example 3: $1,000,000 Home

  • Market Value: $1,000,000
  • Assessed Value: $1,000,000
  • Less: Homestead Tax Credit (if applied): -$4,000
  • Net Taxable Value: $996,000
  • Annual Tax (1.0% rate): $9,960
  • Monthly Escrow: $830

Note: Tax credits shown require annual application and eligibility verification. Actual rates vary by specific taxing districts.

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Section 5

Escrow & Property Taxes

Most mortgage lenders in Union County require property tax escrow accounts to ensure timely payment of property taxes. Your lender collects monthly escrow payments along with your mortgage payment, depositing these funds into a separate escrow account. The lender then pays your property taxes directly to Union County when the April 30th and October 31st deadlines approach.

Lenders typically conduct annual escrow analyses to ensure adequate funds are collected, adjusting your monthly escrow payment if necessary based on actual tax bills and projected changes. Property owners should verify that their lender has current tax information and is making payments on schedule, as you remain ultimately responsible for ensuring taxes are paid on time 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 Union County property taxes due? A: Property taxes are due in two installments: first half due April 30th and second half due October 31st for the current fiscal year.

Q: What tax credits are available and do they require application? A: South Dakota offers several tax credits including the Homestead Tax Credit for qualifying homeowners. Most credits require annual application through the county assessor's office and are not automatically applied.

Q: How does the Homestead Tax Credit work? A: The Homestead Tax Credit limits annual assessment increases on owner-occupied homes and provides a modest reduction in taxable value. You must file an application with the county assessor to receive this credit.

Q: When are properties reassessed in Union County? A: South Dakota requires counties to conduct property revaluations periodically. Contact the Union County Assessor for the current assessment schedule and appeal deadlines.

Q: What are the penalties for late property tax payments? A: Late payments incur penalties and interest charges. Contact the Union County Treasurer's office for current penalty rates and payment options.

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

Q: Why do tax rates vary within Union County? A: Different areas are served by different combinations of school districts, townships, and special districts, each with their own tax levies that combine to create your total tax rate.

Q: How do I appeal my property assessment? A: Contact the Union County Assessor's office for assessment appeal procedures and deadlines, typically following the annual assessment notices.

Verified Sources

Backed by 5 Official Government Sources

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

01
Treasurerunioncountysd.gov
02
Tax Doc
Property Valuations, Tax Rates, Useful Information for ...sandiegocounty.gov
03
Tax Doc
Property Tax | South Dakota Department of Revenuedor.sd.gov
04
Tax Doc
Revenue Categories Property Tax Other Local Taxessandiego.gov
05
County
UNION COUNTY AUDIT REPORT For the Two Years Ended ...legislativeaudit.sd.gov
All sources verified as of 2025 Tax Year

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