Property taxes in Longmont can feel confusing until you see the simple building blocks behind your bill. If you are buying or already own a home, you want a clear picture so you can budget with confidence and avoid surprises. In this guide, you will learn how Boulder County calculates property taxes, how reassessments change your bill, and exactly where to find parcel‑specific numbers for any Longmont property. Let’s dive in.
How Boulder County taxes work
Property taxes in Colorado use a few key pieces that come together to form your bill:
- Market value: the county assessor’s estimate of your home’s full market value.
- Assessment rate: a statewide percentage that converts market value into assessed value.
- Assessed value: market value multiplied by the assessment rate.
- Mill levy: the combined tax rate from all taxing entities that apply to your parcel. One mill equals 1 dollar of tax per 1,000 dollars of assessed value.
The basic formula is straightforward:
- Assessed value = Market value × Assessment rate
- Total tax = (Assessed value × Total mill levy) ÷ 1,000
Two levers change your bill:
- Your assessed value can change when the assessor updates market value or when the statewide assessment rate changes.
- Your mill levy can change each year when taxing authorities set their rates.
A change in market value does not always equal the same change in taxes. Mill levies can rise or fall and partly offset value changes.
What affects a Longmont bill
Your Longmont tax bill is a blend of several local jurisdictions. Most parcels include:
- Boulder County
- City of Longmont
- School district (many Longmont properties are in St. Vrain Valley RE‑1J)
- Special districts, such as fire protection, water and sanitation, metropolitan districts, library, or health service districts
- Voter‑approved bonds, overrides, or temporary levies for any of the above
Every parcel has its own mix of districts. Two homes across town can have different totals because one sits inside a metro district or a different set of special districts. Always check the specific parcel you own or plan to buy.
Where to find your exact numbers
You can verify the market value, assessed value, mill breakdown, and the current tax bill for any Longmont property using local offices and tools. Use these sources:
- Boulder County Assessor’s Office for parcel search, market value, assessed value, property characteristics, and assessment notices.
- Boulder County Treasurer for the tax bill, payment deadlines, prior bills, and the itemized mill levy for the parcel.
- Boulder County GIS or Open Data maps to confirm which taxing districts cover the property.
- City of Longmont Finance for the city mill levy and any city bond information.
- St. Vrain Valley School District (RE‑1J) for school mill levy and bond information when applicable.
- Colorado Department of Local Affairs, Division of Property Taxation (DOLA) for the current statewide assessment rate and valuation standards.
Tip: The treasurer’s bill usually lists the total mills on your parcel and the line‑item jurisdictions. Download the bill and the assessor’s valuation page for your records.
Reassessments, protests, and timing
County assessors update valuations periodically to reflect sales and market trends. Your notice will show the proposed or final market value and the assessed value. It will also list the appeal window. Deadlines are strict, so rely on the dates printed on your actual notice.
If you believe your value is off, start with an informal review with the assessor. Provide recent comparable sales, photos, and cost data that support your case. If you still disagree, you can follow the formal appeal path to the county’s review board and, if allowed by statute, to state‑level review or court.
Separate from valuation, the county treasurer sets billing and payment schedules. Check the treasurer’s information for current due dates and any penalties for late payment.
Key takeaways:
- Reassessments can increase or decrease your assessed value.
- Mill levies are set annually and can move in either direction.
- Buyers should plan for potential tax changes after purchase, which can affect escrow and monthly payments.
Budgeting steps for buyers and owners
Use this simple process to estimate and plan:
- Look up the parcel on the Boulder County Assessor and Treasurer sites. Download the most recent tax bill, valuation page, and the mill levy breakdown.
- Confirm whether the home lies in any special districts that add mills or separate assessments.
- Estimate the first‑year tax amount using current official figures:
- Start from the assessor’s market value or, for a quick gauge, the recent sale price.
- Apply the current statewide residential assessment rate to get assessed value.
- Multiply assessed value by the parcel’s total mills and divide by 1,000 to estimate annual tax.
- Ask the listing agent or title company how taxes will be prorated at closing and how your lender will handle escrow after purchase.
Hypothetical example for illustration only. Confirm current rates and mills before you rely on any estimate.
- Hypothetical market value: 600,000 dollars
- Hypothetical residential assessment rate: 7 percent
- Assessed value: 600,000 × 0.07 = 42,000 dollars
- Hypothetical total mills: 90 mills
- Annual tax: 42,000 × 90 ÷ 1,000 = 3,780 dollars
- Monthly budget estimate: 3,780 ÷ 12 ≈ 315 dollars
Actual assessment rates and mills change and vary by parcel, so always use the county’s current figures for your property.
Common Longmont scenarios
New buyer closing midyear. Taxes are commonly prorated between buyer and seller based on the time each owns the home during the year. Ask how your lender will set up the tax escrow and when they will adjust it after reassessment.
Rising market after a rebound. If your assessed value increases 20 percent and mill levies stay the same, your tax will rise in roughly the same proportion. If taxing authorities reduce mills, the increase could be smaller. Watch both sides: value and mills.
Home in a metro district. A metropolitan district can add notable mills to your tax bill or charge separate annual assessments for debt service. Confirm whether your parcel is in a metro district and review its specific obligations.
Quick checklist before you buy or list
- Pull the parcel’s latest tax bill from the county treasurer.
- Download the assessor’s valuation page and history for the property.
- Confirm all taxing districts that apply to the parcel using county resources.
- Note any voter‑approved bonds or temporary levies.
- Verify the current residential assessment rate with DOLA or the assessor.
- If you plan to appeal, track the dates and instructions printed on your assessment notice.
- For buyers, ask your lender how they will manage and adjust your escrow.
Potential relief programs
Colorado and local offices administer tax relief programs for specific groups, such as seniors or disabled veterans, and some counties offer tax deferral options. Check the Boulder County Assessor and DOLA for eligibility rules, applications, and deadlines.
Work with a local guide
Property taxes do not need to be a mystery. With parcel‑specific research, you can plan your budget, compare homes accurately, and head into closing with clarity. If you want a second set of eyes on a property’s tax profile while you buy or prepare to sell, reach out. My team can help you pull the right documents, interpret what they mean for your budget, and plan next steps with confidence.
Ready to talk through your goals in Longmont and Boulder County? Connect with Bethany J Sartell to schedule a consultation and get your complimentary home valuation.
FAQs
What is the basic Colorado property tax formula?
- Total tax equals assessed value multiplied by the total mill levy, then divided by 1,000. Assessed value equals market value times the statewide assessment rate.
How do I find the mill levy for my Longmont home?
- Check your parcel’s tax bill from the Boulder County Treasurer, which lists the total mills and the itemized taxing entities for your specific property.
Will my taxes change after I buy a home?
- They can. Reassessments and new mill levies may change your bill, and your lender may adjust your escrow, which can affect your monthly payment.
Does my purchase price become the assessed value?
- Not automatically. The assessor considers market data and may factor your sale, but the assessed value is based on the assessor’s market estimate times the assessment rate.
How do I appeal my property valuation in Boulder County?
- Start with an informal review with the assessor using comparable sales and documentation. If needed, follow the formal appeal steps and deadlines printed on your assessment notice.
