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Online Sales and Use Tax Return Filing and Payment

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City of Longmont Sales and Use Tax Online Filing and Payment Portal

NOTE: There is no change to the due date for filing sales and use tax returns. Returns and payment are due on the 20th of each month. Please file your monthly sales and use tax return with the City as usual. If full payment is not included, the City will waive penalties and interest as long as the tax filer files the return and makes contact with the City to make payment arrangements. (3/19/20)


Welcome to the City of Longmont Sales and Use Tax online filing and payment portal. Use this service to quickly and easily file and submit payment, if applicable, for a City of Longmont sales and use tax return.

What do you need for a City of Longmont sales and use tax return?

  • The City of Longmont account number on your sales tax license.

 sales tax license

  • Gross sales and service amount (line 1 on sales/use tax return)
  • Total deductions (line 3-A through 3-L)
  • Amount subject to use tax


* After you have submitted the online return, please follow up by remitting online payment at the same time.

IMPORTANT: Please do not use Google Chrome as your internet web browser to fill out the Sales and Use Tax Online Return Form. We have received reports of duplicate entries occurring while using this form to submit your tax return.

Sales and Use Tax Online Return Form - 2018 - 2020

If you are filing online, the sales and use tax total due and payable must be paid online using an e-check or credit card. Please note: The online payment service is provided by the Statewide Internet Portal Authority (SIPA). The fees below are charged by SIPA and will be added to the transaction amount. 

  • Electronic check: $1.00 per transaction
  • Credit card: $0.75 plus a fee of 2.25% of the total transaction amount

* Only the sales and use tax payment amount will be forwarded to the City of Longmont.

Sales Tax Return Due Date

Sales and use tax returns are due on the 20th day of each month following the end of the filing period. If the 20th falls on a weekend or holiday, the return is due on the next business day. For example, the March 2014 return is due April 21, 2014, since April 20 falls on a weekend.

Who can use this service?

  • Any business with an active City of Longmont sales and use tax license that would like to file and pay online.

After you submit your online return form, you will be sent to a confirmation page that will thank you for submitting the form. There also will be a separate confirmation for your online payment.

If there is revenue due, click the link to proceed to the Statewide Internet Portal Authority (SIPA) website to remit payment. Please ensure that you have your account number, return period and amount handy when you begin the online payment process. SIPA Online Payment service.

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