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Boulder County sales tax rate increases in 2026

This is a county-level change, but it will raise the combined sales tax rate in multiple cities and special districts within Boulder County. Sellers must ensure county tax calculations are updated for all affected locations starting on the effective date.

Ryan Pinkham

Written by Ryan Pinkham

VP of GTM

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Published

What changed

  • Previous rule: Boulder County sales tax applied at a lower county rate.
  • New rule: Boulder County sales tax increases to 1.335 percent.
  • Effective date: January 1, 2026.

Why this matters for cities inside Boulder County

Although the rate change is enacted at the county level, it affects the total tax charged in every jurisdiction where Boulder County tax applies. For example, sellers making taxable sales in the City of Longmont will see a higher combined rate, even though Longmont’s city sales tax rate itself is unchanged.

This type of county-driven change can impact:

  • Cities
  • Home-rule municipalities
  • Special districts
  • Destination-based ecommerce transactions

Example: updated combined rate in Longmont

For transactions sourced within Longmont and Boulder County, the new combined rate will be:

  • State of Colorado: 2.900%
  • RTD/CD: 1.100%
  • Boulder County: 1.335%
  • City of Longmont: 3.530%
  • Combined total sales tax rate: 8.865%

Who this affects

  • Sellers with physical locations anywhere in Boulder County
  • Remote sellers shipping taxable goods into Boulder County
  • Ecommerce businesses collecting Colorado destination-based sales tax
  • CPAs and accountants managing Colorado sales tax compliance
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If you use TaxCloud

TaxCloud automatically updates its sales tax calculation engine across all jurisdictions, including county-level rate changes and their downstream effects, so sellers do not need to manually adjust rates.

Next steps for sellers

  • Update sales tax calculation to apply the new Boulder County rate for all affected locations starting January 1, 2026.
  • Review combined rates in cities and special districts within Boulder County to confirm downstream impacts.
  • After calculation is correct, ensure January 2026 transactions are reported accurately on February 2026 sales tax returns.

Official sources:

  1. 1.
    Boulder County Goverment Sales and Use Tax. Source link
  2. 2.
    City of Longmont Goverment Sales and Use Tax. Source link

Disclaimer

TaxCloud provides sales tax compliance solutions. We do not provide legal or tax advice. For questions about your specific tax situation or filing requirements, we recommend consulting a qualified sales tax accountant.

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