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Transferable Development Credits (TDC) FAQs - Seller

What are TDCs?

TDCs are Transferable Development Credits. Under regulations adopted by the Board of County Commissioners, houses above 6,000 square feet may only be constructed in unincorporated Boulder County if the landowner purchases TDCs, subject to certain exemptions. TDCs are measures of single family residential floor area. There is a sliding scale to determine the number of TDCs needed to build additional floor area. See chart below.


 Number of square feet

 Number of Credits

 Total Additional Square Footage

Total Credits for Additional Square Footage 

 1st 500




 2nd 500




 3rd 500




 Each additional 500 square feet




* Minor additions (under 200 square feet) may be exempt; See below.

Who Can Sell TDCs?

Owners of legal building lots with legal access who are willing to permanently restrict development on their properties may obtain TDC Certificates, subject to meeting certain qualifications, as well as sell their TDCs. The number of TDCs available from a parcel will depend on its location in the mountains or the plains and whether all development is prohibited, so that the parcel remains vacant land forever, or whether existing or future structures are limited to no larger than 2,000 square feet.

How Many TDCs May I Receive If I agree to Restrict the Size of My Current or Future House on My Property?

The chart below shows the number of TDCs available for properties limited to certain sizes. The same rules apply to mountain and plains properties.

Developed Parcel Residential Floor Area

Number of TDCs Available

2000 square feet

2 TDCs

1500 square feet

3 TDCs

1000 square feet

4 TDCs


How Many TDCs May I Receive If I Agree to Maintain My Property As Vacant Land?

If you restrict your property with a conservation easement, you will be entitled to five TDCs for mountain property and 10 TDCs for plains property.

How Many TDCs My I Receive If I Agree to Convey My Property to the County?

If your property is located in the Mountains, you are entitled to seven TDCs. If your property is located in the Plains you are entitled to 12 TDCs for conveying your parcel to the County.

Conveyance to the County is subject to the County accepting your offer, in its sole discretion.

What is Included in the Mountain Area and the Plains Area?

The Mountain Area includes the area west of CO 93 from its intersection with the South county line to the City of Boulder, West of the City of Boulder city limits, West of US 36 from the City of Boulder to CO 66, and West of the St. Vrain Supply Canal from CO 66 to its intersection with the North county line. See Land Use Code Section 18-178A.
The Plains Area includes all areas of the County that are not part of the Mountain Area.

How is the Size of Basements, Porches, and Garages Counted in Determining My Eligibility for TDCs?

Residential floor area includes garages, basements and residential accessory structures, but does not include the area of any covered porches. Gazebos and carports under 200 square feet each, up to 400 square feet total are exempt.

What Are the Benefits of Selling TDCs?

If you intend to keep your house at a modest size, or don't want to develop your property, then selling TDCs can provide you with funds for another purpose of your choice.

How Much is a TDC Worth?

It depends on the market. You can sell TDCs to any party who wishes to buy them at a price you negotiate. Sellers of TDCs are required to report the sales price to the TDC Clearinghouse and that information is publicly available, and will be regularly updated.
See the TDC Marketplace
for market values.

Can I Sell a Fraction of a TDC?

No. Fractional TDCs will not be recognized by Boulder County or the TDC Clearinghouse, and will not be valid for building permit issuance.

How Do I Sell TDCs?

Sellers of TDCs may register their TDCs with the TDC Clearinghouse so that buyers may contact you directly or the TDC Clearinghouse can notify you of buyers looking to purchase TDCs. Buyers who have registered their interest in purchasing TDCs are listed in the TDC Marketplace and you may contact them directly. You may also contact parties on your own and ask them if they would like to buy TDCs. Generally, property owners who wish to build houses above the threshold size in Boulder County are potential buyers of TDCs.

How Do I Know if I'm Entitled to TDCs?

To be entitled to TDCs, you must have a legal building lot with legal access and you must agree to keep your property vacant or with a house of no more than 2,000 square feet of residential floor area. If you meet these criteria, you need to submit a TDC Determination Application to the TDC Clearinghouse. The form is available for download from the TDC Determination Application page. The County will determine if you are eligible for TDCs and the number of TDCs available from your property.

Am I Entitled to Additional TDCs for the Significant Conservation Values of My Property?

You may be entitled to bonus TDCs, with a maximum of five, for significant conservation values of your property. This is a determination made by the Boulder County Parks and Open Space Department. Be sure to provide the information on the TDC Determination Application Form requesting that the Parks and Open Space Department look at these values and decide whether your property is entitled to bonus TDCs.

Am I Entitled to Additional TDCs If My Property is in the Floodway and I Remove Structures From My Property?

You may be entitled to bonus TDCs, with a maximum of five, for significant floodway mitigation activities on your property. This is a determination made by the Boulder County Transportation Department. Be sure to provide the information on the TDC Determination Application Form requesting that the Transportation Department look at the floodway mitigation potential for your property and decide whether your property is entitled to bonus TDCs.

Am I Entitled to Additional TDCs if My Property is Historically Significant?

You may be entitled to bonus TDCs with a maximum of five, if your property is historically significant, whether it is currently landmarked or has the potential to receive an historic landmark designation in the future. Whether your property is entitled to bonus credits for historic significance is a determination made by the Boulder County Land Use Department. Be sure to request that the Land Use Department evaluate whether your property is entitled to bonus TDCs for historic significance on the TDC Determination Application Form.

Am I Entitled to TDCs for My Property, Which Has No Legal Access?

No. Legal access is a requirement for issuance of TDCs. If you're not sure if your property has legal access, you can ask the County for a determination when you submit a TDC Determination Application Form or contact the Boulder County Transportation Department.

I'm Not Sure if My Property is a Legal Building Lot. How Can I Find Out if I'm Entitled to TDCs?

You must have a legal building lot to be eligible for TDCs. The County Land Use Department will determine whether your property is a legal building lot as part of its review of your TDC Determination Application Form. You may also submit a Building Lot Determination Form to the Boulder County Land Use Department if you are just interested in knowing if you have a legal building lot.

My Lender Placed a Mortgage or Deed of Trust on My Property. Does That Limit My Right to TDCs?

You will need to obtain a subordination agreement from your lender before your TDC Certificates will be issued. That means your lender will recognize the development restrictions you place on your property through the TDC process. Please contact your lender as soon as possible to discuss this matter. The TDC Clearinghouse can provide you with additional information and assistance.

What is the Procedure for Issuance of My TDCs?

First, submit your TDC Determination Application Form to the County. Once the TDC Determination is made, the information will be provided to you and to the TDC Clearinghouse. If you wish to proceed with issuance of TDCs, you must submit a title commitment to the TDC Clearinghouse for review. The TDC Clearinghouse will review your title, determine if there are any mortgages or deeds of trust encumbering the property that need to be subordinated and if there are any other title issues to resolve. The TDC Clearinghouse will draft the conservation easement or restrictive covenant for you to sign. After the conservation easement or restrictive covenant is signed, and all other requirements are satisfied, the TDC Clearinghouse will issue your TDC Certificates.

How Long Will it Take for My TDC Certificates to Be Issued?

Generally, the TDC Determination Application will be reviewed within 10-20 business days by the County Land Use and Transportation Departments. Requesting bonus credits will extend the process because review by the Parks and Open Space Department may require a site visit to your property and additional information. After your TDC Determination is issued, the TDC Clearinghouse will review title and draft documents. This process should take approximately 5-10 business days from submission of required documentation. If a conservation easement is required to protect significant conservation values, it will need to be tailored to the property and this will extend the process. If you need to subordinate a mortgage or deed of trust, the lender response may delay issuance of your TDC Certificates.

Are There Costs to the Applicant for Issuance of Bonus TDCs for Significant Conservation Values?

There is a $100 fee that is paid to the Parks and Open Space Department to evaluate your property and determine if there are significant conservation values on your property that justify an award of bonus TDCs. If bonus TDCs are awarded for significant conservation values, then the Parks and Open Space Department will draft a site specific conservation easement to preserve and protect those values. The County will require that a Phase I environmental assessment be prepared for your property before the bonus TDCs are issued. The cost of the Phase I will be the applicant’s responsibility.

What Can I Do to Speed Up the Process?

You can speak to your lender in advance and explain your need for a subordination agreement. You can also order a title commitment in advance and submit it to the TDC Clearinghouse for review prior to receipt of your TDC Determination.

How Will the Sale of TDCs Affect the Value of My Property?

The value of your property is determined by the market. Many factors influence the value of properties. Until there is a body of sales data available, it is impossible to answer this question.

Is the Sales Price for My TDCs Public Information?

Yes. You are required to report the sale of your TDCs to the TDC Clearinghouse within five business days after the closing of your sale. The Seller Reporting Form can be downloaded in the TDC Forms Section on this site.

What Happens if I Don't Report the TDC Sale?

Your buyer will not be able to receive a new TDC Certificate until you report the sales information. The buyer needs a TDC Certificate issued in the buyers name to submit a building permit application.

Does the Number of TDCs to Which I'm Entitled Depend on My Location in the Mountains or the Plains?

Yes, if you are agreeing your property will remain vacant.
No, if you are agreeing to restrict the size of your home.

What's the Difference Between the Restriction on Size of Development on My Parcel and the County-wide Size Threshold?

The restricted size of your parcel is the maximum size to which you agree to restrict development on your parcel to no more than 2,000 square feet of residential floor area in order to obtain TDCs. The County-wide Size Threshold is the size above which TDCs are required to build your residence, 6,000 square feet of residential floor area. If you wish to build a home larger than 6,000 square feet, then you must submit TDC Certificates with your building permit application, subject to certain exemptions.

What are Conservation Easements and Restrictive Covenants?

Conservation easements and restrictive covenants are agreements between the landowner and the County that restrict future development and use of your property. They restrict the uses of your property in perpetuity and are recorded in the real property records of Boulder County.

I Believe That the Size of My House is Incorrect in the County Records. How Can I Challenge the Size Determination?

You should speak to the Land Use Department and be prepared to explain why your measurements are correct.

If TDC Certificates are Issued From My Property, Can I Later Purchase TDCs to Use for Development on My Property?

TDCs cannot be used to allow residential development on vacant properties from which TDCs have been severed. Once you place the restrictive covenant or conservation easement on your property, limiting its use to vacant land, you cannot change your mind and buy TDCs to allow residential development. If TDCs were severed from your property with a building limit of less than 2,000 square feet of residential floor area, TDCs may be used to allow greater development on your property, but only to allow the construction of a residence up to 2,000 square feet in size, and only when an amended restrictive covenant is placed on the property.

Is there an exemption for a very small addition to my home?

A one time allowance of up to 200 square feet of residential floor area may be exempt from the requirement to purchase Development Credits, for a minor modification to your home, such as the addition of a closet or small bathroom. The additional residential floor area would still need to be approved through the Site Plan Review process, if applicable.

Please Note: The information provided in this website is for general purposes only. The TDC Clearinghouse and Clearinghouse Administrator do not provide legal advice. Interested parties should consult their own legal and tax or financial counsel for information on their specific circumstances and advice on the legal consequences of obtaining, buying, selling, or using Transferable Development Credits. Although the Clearinghouse has used best efforts to ensure that the information provided on this site is accurate and reliable, we do not guarantee that it is fully correct or complete in every respect.

Transferable Development Credits (TDC) Clearinghouse Logo


Boulder County Transferable Development Credits (TDC) Clearinghouse

Main: 303-441-3190
Fax: 303-441-4794

Mailing Address

Boulder County Attorney
PO Box 471
Boulder, CO 80306