Montana cannabis testing requirements

Required tests

• Potency
• Pesticides
• Residual solvents
• Heavy metals
• Microbials
• Mycotoxins
• Moisture
• Foreign matter

ISO/IEC 17025 accreditation

Required. ARM 42.39.603: an ISO/IEC 17025:2017 accreditation certificate and audit reports must be filed before the licensing inspection is scheduled, and accreditation must cover every method in ARM 42.39.614 at all times.

Notes

• Rules: ARM 42.39.6 (testing laboratories), chiefly 42.39.614 and its Quality Assurance Testing Requirements Appendix v1.0 (Aug 24, 2024).
• The panel varies by product: flower gets everything except solvents; solvent-based concentrates skip microbials; infused products need potency and microbials; pre-rolls made from tested flower need potency only.
• Heavy metals (arsenic, cadmium, lead, mercury) are tested at random, not on every batch (ARM 42.39.614(17)).
• Microbials: Salmonella, STEC and Aspergillus (4 species) not detectable in 1 g. Mycotoxins: total aflatoxins and ochratoxin A, 20 µg/kg each. Moisture fails above 15%.
• Lab oversight moved from the health department (DPHHS) to Revenue under HB 128 (2023), effective July 1, 2023; a 2026 proposal removes the last DPHHS references from the rules.
• In Oct 2025 the department said only one testing lab was operating in the state, down from three a year earlier. Its plan to raise the test batch cap from 5 to 15 lb was dropped in March 2026.
• Composite test samples are prohibited, and multi-strain harvest lots have been banned since Feb 24, 2025.