Infrastructure Data Taxonomy

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How is the Infrastructure Data Taxonomy Used?

The IDT Table of Contents serves as a quick reference of the taxonomy, in which infrastructure assets are categorized up to five levels. The first level is determined by broad infrastructure categories, which are then detailed further by increasingly granular differentiators as needed. The five levels of differentiation found within the IDT are the sector, sub-sector, segment, sub-segment, and asset type.

In describing a given infrastructure asset, the general convention is to use the greatest level of detail possible. If there is insufficient information to identify an asset at a greater level of detail, a less-detailed level may be used.

Some infrastructure assets fall into multiple categories of the taxonomy. For this reason, some concepts may be found listed within multiple sectors. This is called a cross-sector reference.

For example, in referring to the same nuclear power plant, the government and private sector could reference it either as a nuclear plant, a nuclear site, or a nuclear facility. The example below shows how this specific nuclear facility would be classified using the IDT:

  • Sector: The nuclear plant is identified as being part of the Nuclear Reactors, Materials, and Waste Sector.
    • Subsector: Within the Nuclear Reactors, Materials, and Waste Sector, the nuclear plant is designated as part of the Nuclear Facility Subsector.
      • Segment: The nuclear plant is identified as part of the Nuclear Power Plant Segment to recognize the plant's purpose.
        • Subsegment: Finally, the nuclear plant can be categorized as being part of the Boiling Water Reactor Subsegment to recognize how the plant produces energy.

Update to the Infrastructure Data Taxonomy

Taxonomy assignments are based on the DHS Infrastructure Taxonomy V.4, issued in June 2011, and do not reflect changes to the taxonomy outlined in Presidential Policy Directive/PPD-21, issued on February 21, 2013.

As of April 2021, the Infrastructure Security Division is initiating an update of the Infrastructure Data Taxonomy to ensure that it reflects the current realities of the critical infrastructure space. The taxonomy will be updated in an iterative process, with continuous engagement of stakeholders across the infrastructure protection community.

Questions about the update

If you would like to provide input to the Infrastructure Data Taxonomy update, please contact Carmen Zapata at


Learn how the Infrastructure Data Taxonomy can support your organization's homeland security efforts by contacting the CISA Gateway Help Desk at or 1-866-844-8163.