City of Westminster, Colorado implements 4.25% sales tax rate beginning January 1, 2026
Written by Alex Lamachenka
Head of DemandGen
Published
What’s changing
Ballot Measure 3H passed, authorizing a 0.4 percent increase to the existing city rate. New rate effective January 1, 2026:
- City sales and use tax: 4.25% (up from
3.85%)
Revenue will fund:
- Staffing for new and existing fire/EMS stations
- Construction of a new Central Westminster fire station
- Rebuild of Fire Station 3
- Emergency vehicles and equipment
- At least $2 million annually for neighborhood street improvements
Westminster is a Colorado home-rule city, meaning its tax is administered and collected independently from the Colorado DR 1002 system.
Who this affects
- Remote sellers with Colorado economic nexus
- Marketplace facilitators
- Colorado retailers filing in home-rule jurisdictions
- Anyone using manual tax overrides or city-specific rate tables
Under-collecting after January 1 will create calculations and filing discrepancies with Westminster’s Tax & Revenue Division.
Why this matters
Colorado home-rule cities impose their own rates, returns, audits, and deadlines. If your system does not automatically update city-level rates, you may:
- Under-collect tax
- Receive discrepancy notices
- Trigger interest and penalty assessments
- Disrupt marketplace reporting flows
Because this is a voter-approved increase with a fixed start date, there is no grace period.
Next steps
- Update POS, ERP, and checkout rate tables
- Confirm ZIP/address rules for Westminster boundaries
- Review marketplace or ecommerce overrides
- Ensure January 2026 filings reflect the new 4.25% rate
Official Source:
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