What NI 43-101 Means and What a Technical Report Tells You

NI 43-101 sets how Canadian mining companies disclose technical data. What resource categories, QPs, PEAs, PFSs and FSs mean, and what they do not.

Key takeaways

NI 43-101 governs mining disclosure in Canada, and the version in force is the consolidated instrument effective June 9, 2023.
A technical report supporting a material first-time resource, reserve or PEA must be filed no later than 45 days after the disclosure.
Only reserves have demonstrated economic viability, which requires at least a pre-feasibility study, and resources, including inferred resources, do not.

National Instrument 43-101 is the Canadian rule that governs how mining companies disclose scientific and technical information about their projects. A technical report written under it tells you what a qualified person found and on what assumptions. It does not tell you that a mine will be built, or that the project is worth what its economic study says.

What the rule covers

NI 43-101 applies to written and oral disclosure by issuers reporting in Canada. The version in force is the consolidated instrument effective June 9, 2023, as listed by the BCSC and the Alberta Securities Commission. The Canadian Securities Administrators published a proposed repeal and replacement for comment on June 12, 2025. As of September 24, 2026, the regulators’ sites list that proposal as proposed, with no final effective date.

Main requirements of the current instrument:

Disclosure must be based on information prepared by or under the supervision of a qualified person (QP), and the release must name the QP and state their relationship to the issuer.
Resources and reserves must be reported only in the CIM Definition Standards categories.
A technical report must be filed to support certain disclosure, such as a first-time resource estimate, reserve or preliminary economic assessment that is a material change. The filing deadline is no later than 45 days after the disclosure.
In the situations listed in section 5.3, the QP writing the report must be independent of the issuer. Producing issuers have some exemptions.

A QP must hold a degree in geoscience or engineering, have at least five years of relevant experience, and be in good standing with a professional association.

Resource and reserve categories

The CIM Definition Standards set out five categories. The order runs from least confident to most confident.

Category	What it means under CIM	Economic viability shown?
Inferred resource	Quantity and grade estimated from limited geological evidence and sampling	No
Indicated resource	Estimated with enough confidence to apply modifying factors	No
Measured resource	Enough confidence to support detailed mine planning	No
Probable reserve	Economically mineable part of an indicated (sometimes measured) resource	Yes, at least a pre-feasibility study
Proven reserve	Economically mineable part of a measured resource	Yes, at least a pre-feasibility study

A mineral resource requires “reasonable prospects for eventual economic extraction.” That is a lower bar than a reserve. NI 43-101 requires resource disclosure to state, with equal prominence, that resources that are not reserves do not have demonstrated economic viability. CIM says inferred resources must not be converted to reserves, although it is “reasonably expected” that most could be upgraded to indicated with more drilling.

PEA, PFS and FS

Study	Definition	Can it use inferred resources?	Can it support reserves?
Preliminary economic assessment (PEA)	A study, other than a PFS or FS, with an economic analysis of the potential viability of mineral resources	Yes, with mandatory cautionary language	No
Pre-feasibility study (PFS)	A comprehensive study of a range of options, at a stage where a preferred mining method is established	Not in the economic case	Yes
Feasibility study (FS)	A comprehensive technical and economic study of the selected development option, with detailed assessment of modifying factors	Not in the economic case	Yes

Modifying factors are the mining, processing, metallurgical, infrastructure, economic, marketing, legal, environmental, social and governmental considerations used to turn a resource into a reserve. A PEA that includes inferred resources must say the assessment is preliminary, that inferred resources are too speculative geologically to have economic considerations applied to them, and that there is no certainty the results will be realized.

The math: from contained ounces to something smaller

A hypothetical gold project reports 10.0 million tonnes at 1.5 g/t, with 40% of the tonnes in the inferred category. The numbers are invented for illustration.

Contained gold: 10,000,000 x 1.5 g = 15,000,000 g, divided by 31.1035 g per ounce = about 482,000 ounces.
Ounces in measured and indicated only (60%): about 289,000 ounces. These are the only ounces that can become reserves.
At an assumed 90% metallurgical recovery: about 260,000 recoverable ounces before mining dilution, mining losses and pit or stope design.

The headline “482,000 ounces” and the number of ounces a feasibility study might show can be far apart. Every step in that chain is disclosed somewhere in the technical report.

What investors misread

“43-101 compliant” is a disclosure standard. It means the report follows the rules. It says nothing about whether the project is economic or financeable.
Resources are not reserves. Only reserves have demonstrated economic viability.
PEA numbers are preliminary. An after-tax NPV and IRR in a PEA can rest on inferred resources, and the metal price assumptions drive the result. Check the price deck and the sensitivity tables.
Historical estimates. A company can cite an older estimate only if it names the source and date, comments on reliability, and states that a QP has not done enough work to classify it as a current resource.
Exploration targets. Ranges of potential tonnes and grade are permitted only when the company states, with equal prominence, that they are conceptual in nature.
Dates. Every report has an effective date. Metal prices, costs and permits may have changed since.
Who wrote it. Check the QP certificates at the back: their experience, and whether they are independent of the issuer.

What to watch

Technical reports and QP consents filed on SEDAR+ within 45 days of a material resource or study announcement.
CSA notices on the final form of the replacement for NI 43-101.
Changes in category mix between successive resource updates, especially the share that is inferred.
The metal price and cost assumptions in any PEA, PFS or FS, compared with the date the study was released.

Sources

Frequently asked questions

What does NI 43-101 compliant mean?

NI 43-101 compliant means a mining company’s disclosure follows the Canadian rule for scientific and technical information about mineral projects. It is a disclosure standard. It does not say whether a project is economic or financeable. The rule requires disclosure to be based on work by a named qualified person and resources to use CIM Definition Standards categories.

What is the difference between a mineral resource and a mineral reserve?

A mineral resource needs reasonable prospects for eventual economic extraction, a lower bar than a reserve. A reserve is the economically mineable part of an indicated or measured resource, supported by at least a pre-feasibility study. Under the CIM Definition Standards, resources run from inferred to indicated to measured, and reserves are probable or proven.

What is the difference between a PEA, PFS and feasibility study?

A preliminary economic assessment analyzes the potential viability of mineral resources and can use inferred resources with mandatory cautionary language, but cannot support reserves. A pre-feasibility study compares a range of options once a preferred mining method is established. A feasibility study assesses the selected development option in detail. Both a PFS and an FS can support reserves.