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Guidance

Bats: mitigation class licence to allow low impact work on bat roosts (CL21)

Register as an ecological consultant to disturb or capture common bats, or damage or destroy low conservation status roosts; find out how to register a site and if you need to pay.

From:
Natural England
Published:
6 April 2017
Last updated:
30 July 2026 — See all updates

Applies to England

Documents

Guide to using bat mitigation class licence CL21: registration criteria, how to apply and if you need to pay

HTML

Annex A: application form

PDF, 2.2 MB, 1 page

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Annex B: application form

PDF, 2.39 MB, 1 page

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Annex C or Annex D: application form - use for either annex

PDF, 1.7 MB, 1 page

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Details

Natural England is phasing out the CL21 licence. This means we are not accepting applications to become a registered consultant. Existing registered consultants will not be able to register new sites after 14 December 2026.  

The CL21 is being closed as we transition to the CL47 Bat Earned Recognition Licence. Bat earned recognition covers more bat species and roosts than CL21 at all accreditation levels and provides greater flexibility both before and after a site is registered.    

To ensure continuity, existing CL21 registered consultants have been contacted and offered a streamlined route to become accredited on bat earned recognition.

If you are not a registered CL21 consultant, you can still apply for bat earned recognition if you meet the application criteria.

CL21 licence

The bat ‘low impact’ licence (CL21) is a mitigation class licence that allows a registered ecological consultant to interfere with certain bats and their roosts. There are 4 annexes to this licence that specify:

  • which species and roost type you can interfere with
  • areas in England where you can carry out work

Use the guide to find out:

  • the criteria you must meet to become a registered consultant
  • what the licence allows you to do
  • which licence annex is right for you
  • if you’ll need to pay to register a site on your licence
  • how to apply and which form to use
  • how to download and fill in the forms

Use the relevant application form for the annex you choose.

Updates to this page

Published 6 April 2017
Last updated 30 July 2026 Show all updates

  1. Added new information on how Natural England is phasing out the CL21 licence. The CL21 is being closed as we transition to the CL47 Bat Earned Recognition Licence.

  2. Updated the availability of training workshops for the CL21 licence. There are no planned training workshops.

  3. Added new information about when you do not need to pay for this licence.

  4. Updated guide with details of when you may need to pay for site registration.

  5. Replaced application forms for annexes A, B, and C or D with updated versions.

  6. County of Devon has been added to the list for Annex C of the bat low impact licence.

  7. Application forms for each annex added.

  8. Added guidance on 4 annexes you can use with this licence.

  9. Replaced application form with updated version.

  10. First published.

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