What Is the 90% Rule in Canadian Tax (2026)? SR&ED, GST/HST Itcs & CRA “all or Substantially All” Explained

The 90% rule canada tax standard, more formally the Canada Revenue Agency’s “all or substantially all” test, is one of the more consequential and least understood thresholds in Canadian tax compliance, and in 2026 it continues to draw attention from founders, CFOs and tax managers facing CRA scrutiny. In plain terms, the rule treats a use, activity or expenditure as fully qualifying when roughly 90% or more of it meets the statutory purpose, while anything below that line typically forces apportionment or outright denial. This administrative benchmark reaches across two of the most audited programs in the country: the Scientific Research and Experimental Development (SR&ED) incentive and the GST/HST input tax credit (ITC) regime.

This guide explains where the test appears, how the CRA applies it in audits, and what documentation you need to support a claim through a reassessment.

Who this is for: founders, CFOs, controllers, tax managers and in-house counsel who need an operational test and a documentation checklist to help avoid reassessment and prepare for CRA audits of SR&ED claims and GST/HST input tax credits. If you allocate costs between eligible and ineligible uses, this rule governs how much you can keep.

Quick Answer: What Is the 90% Rule in Canada?

The 90% rule in Canada is the practical shorthand for the “all or substantially all” standard used by the CRA. When a statute or program requires that “all or substantially all” of something be devoted to a qualifying purpose, the CRA administratively interprets “substantially all” as approximately 90% or more. Meet or exceed that line and the item is generally treated as entirely qualifying; fall below it and you must apportion, or, in some cases, lose the benefit entirely. The 90% figure is an administrative guideline rather than a fixed statutory bright line, and courts assess “substantially all” on the facts of each case.

One-Line Legal Summary of the 90% Rule Canada Tax Test

The standard draws its force from the statutory wording of the Income Tax Act (for SR&ED) and the Excise Tax Act (for GST/HST), and is operationalised through CRA administrative guidance including the SR&ED eligibility pages and GST/HST publications on input tax credits. The 90% figure is the CRA’s long-standing working reference point for “substantially all,” and courts reviewing these provisions have generally accepted that “substantially all” denotes a high proportion approaching the whole, assessed on the facts.

Where the “All or Substantially All” Test Appears: SR&ED vs GST/HST vs Other Statutes

The phrase “all or substantially all” recurs throughout Canadian tax legislation, but three contexts dominate real-world compliance work. Understanding how the 90% rule canada tax threshold operates differently in each is the first step to supporting a claim.

SR&ED Program, How “All or Substantially All” Governs Eligibility

Under the SR&ED program, the “all or substantially all” test surfaces when claimants seek to include expenditures that are not purely experimental but are directed to, or support, qualifying work. The CRA’s SR&ED eligibility guidance sets out the tests used in audits to determine whether work constitutes basic research, applied research or experimental development, and whether supporting work is “commensurate with the needs” of that qualifying work.

Where the test bites hardest is the treatment of certain shared expenditures and the allocation of salaries, materials and overhead. Under the SR&ED rules, if an employee is engaged “all or substantially all” of their time in prosecuting eligible SR&ED, the full associated salary can generally be included. If the proportion drops below that line, the claimant must apportion the cost based on the time actually spent. The practical effect is that a staff member running at 92% eligible activity is treated differently from one at 88%, even where the underlying science is similar. Claimants should note that the detailed SR&ED expenditure and allocation rules are technical; confirm current treatment against the CRA guidance applicable to the claim year.

GST/HST Input Tax Credits, When ITCs Are Denied or Apportioned

In the GST/HST context, the 90% rule canada tax threshold affects how much of the tax paid on an input a registrant may recover as an input tax credit. The core principle grounded in the Excise Tax Act is that ITCs are available to the extent that a property or service is acquired for consumption, use or supply in the course of commercial activities. For certain inputs, the legislation applies “all or substantially all” rules: for example, where a person who is not a financial institution acquires property or a service for use 90% or more in commercial activities, it may be treated as acquired for use entirely in commercial activities (and the reverse applies for 90%-or-more non-commercial use).

Between those poles, registrants must apportion the ITC using a method that is fair and reasonable and used consistently throughout the year.

This is where mixed-use assets, a vehicle, a building, software licences, professional fees, generate the most audit disputes. A registrant that claims a full ITC on an input used only 85% in commercial activities may have over-claimed, and the CRA can reassess the excess, often with interest and potentially penalties. Note that capital personal property and capital real property have their own specific ITC rules under the Excise Tax Act, which should be confirmed for the particular asset.

Other Contexts Where Courts Apply the Standard

Beyond SR&ED and GST/HST, “all or substantially all” appears in provisions dealing with such matters as farming and fishing property, small business corporation share tests and various rollover rules. The Tax Court of Canada and the Federal Court of Appeal have interpreted the phrase across these areas, and the jurisprudence generally treats “substantially all” as a high proportion of the whole, with the CRA’s 90% administrative line serving as a practical reference point rather than a rigid statutory bright line. Courts retain discretion to find that “substantially all” is met on the facts even where the arithmetic is slightly under 90%, though relying on that discretion is risky.

How CRA Applies the 90% Rule Canada Tax Test in Audits and Rulings

Knowing the threshold is only half the battle; the harder question is how the CRA measures the proportion in practice. Auditors do not simply accept a taxpayer’s assertion that “92% of this was eligible.” They reconstruct the allocation from the records, test the methodology, and probe the commercial purpose behind each cost.

In both SR&ED and GST/HST audits, the CRA’s approach typically follows a recognisable sequence: establish the facts, identify the correct allocation basis, assess the quality of the records supporting that basis, test the nexus between the cost and the qualifying purpose, and finally evaluate commercial purpose and reasonableness. A claim that looks defensible on paper can collapse if the underlying records do not substantiate the allocation the taxpayer has reported.

CRA Evidence Weight, Contemporaneous Records Win

One of the most important factors in surviving a 90% rule canada tax audit is contemporaneous documentation. The CRA generally gives more weight to records created at the time the work was done or the input was acquired than to reconstructions prepared after an audit letter arrives. For SR&ED, this means dated project logs, time sheets allocating hours to specific eligible activities, lab notebooks, design records and internal progress memos. For GST/HST ITCs, it means usage logs, mileage records, floorplans or square-footage allocations, and clear links between invoices and commercial use.

After-the-fact estimates, round-number allocations and allocations that conveniently land just above 90% invite skepticism. Where contemporaneous evidence is thin, the CRA may substitute its own, lower, allocation, and the burden then generally falls on the taxpayer to displace it.

Apportionment Methods the CRA Accepts

When use falls below the 90% threshold and apportionment is required, the CRA expects a method that is fair, reasonable and consistently applied. Accepted approaches include:

• Usage logs. Direct measurement of how an asset is actually used, kilometres driven for commercial versus personal purposes, hours of machine time on eligible versus non-eligible work.
• Time-based allocation. Employee hours tracked against specific projects or activities, supported by time sheets, for salary and wage apportionment.
• Value-based or square-footage allocation. For real property and shared facilities, apportionment by floor area or relative value devoted to commercial versus exempt or personal use.

Whichever method is chosen, consistency matters. Switching methods between periods to maximise recovery can be a red flag, and the CRA will scrutinise any method that produces results favourable to the taxpayer without a robust factual basis. This is also where early engagement of counsel can help: a tax lawyer can engage the CRA over the allocation methodology before an assessment is finalised, often narrowing the dispute.

Practical Examples and Worked Calculations (SR&ED and GST/HST)

Abstract thresholds become clearer with numbers. The following worked examples illustrate how the 90% rule canada tax test can play out on both sides of the line, and how small shifts in allocation change the outcome. The figures are illustrative only.

Example A: SR&ED Project at 92% Eligible Activity

Suppose a software company dedicates one senior developer almost entirely to resolving a genuine technological uncertainty, building an experimental data-compression algorithm with an uncertain outcome. The developer’s annual salary is $120,000. Time sheets show that 92% of her logged hours went to the experimental development work, with the remaining 8% on routine maintenance of an existing product.

Because 92% exceeds the 90% threshold, the company may generally treat the developer as having been engaged “all or substantially all” in SR&ED, and include the full $120,000 salary as a qualifying SR&ED expenditure (subject to the program’s other rules). The recommended documentation is a dated time-tracking record broken down by project and activity type, a project description setting out the technological uncertainty, and progress memos showing the experimental nature of the work. Without those records, an auditor could recharacterise the split, and if the eligible proportion is pushed below 90%, the company loses the benefit of the “all or substantially all” treatment for that salary and must apportion.

Example B: Mixed-Use Purchase at 88% Commercial Use

Now consider a registrant that acquires a $50,000 piece of equipment, paying $6,500 in HST (illustrated at a 13% rate; applicable GST/HST rates vary by province). Usage logs show the equipment is used 88% in commercial activities that generate taxable supplies, and 12% in making exempt supplies.

Because commercial use is 88%, below the 90% line, the registrant generally cannot treat the equipment as used entirely in commercial activities. Instead, the ITC is apportioned. On a simple proportional basis, the recoverable ITC is 88% of $6,500, or $5,720, leaving $780 of HST non-recoverable. Had the commercial use instead been 90% or higher, the full $6,500 could potentially have been claimed. (For capital property, specific ITC rules in the Excise Tax Act apply and should be confirmed for the particular asset.)

Sensitivity: Why Allocation Near the Line Is High-Risk

The examples above show why allocations clustered around the 90% line carry outsized audit risk. Move Example B’s commercial use from 88% to 91% and the registrant may move from apportioning to claiming a full ITC. Move Example A’s eligible SR&ED time from 92% to 89% and the full-salary treatment is lost. Because the consequences are close to binary at the threshold, the CRA tends to audit borderline allocations closely, and taxpayers whose records cannot withstand that scrutiny face the largest reassessments. The practical lesson is to build in a comfortable margin and to document rigorously whenever an allocation sits within a few points of 90%.

Comparison Table: SR&ED vs GST/HST Under the 90% Rule

Documentation and Defence: What to Prepare Before and During an Audit

The difference between a well-supported 90% rule canada tax position and a costly reassessment often comes down to documentation prepared before any audit letter arrives. Finance teams should assemble and maintain the following for every claim or allocation that depends on the “all or substantially all” standard:

• Project descriptions and statements. A dated narrative identifying the technological uncertainty (for SR&ED) or the commercial purpose (for GST/HST), establishing the qualifying objective up front.
• Time sheets and activity logs. Contemporaneous records allocating employee hours and asset usage to specific projects and purposes.
• Expense and procurement records. Invoices, vouchers and purchase orders linked to the relevant project or commercial activity.
• Internal memos explaining use. Short, dated notes documenting why an asset or cost was allocated as it was, created at the time the decision was made.
• Allocation tables. A clear, reproducible calculation showing the methodology and the resulting percentage, with supporting source data.

Templates and Language That Help Your Position

A well-drafted project statement that expressly frames work in terms the program recognises, “experimental development undertaken to resolve a technological uncertainty,” or “acquired for use in making taxable supplies”, signals to an auditor that the taxpayer understood the test and applied it deliberately. An allocation table that shows the inputs, the measurement basis, the arithmetic and the resulting percentage lets an auditor verify the figure quickly, reducing friction. Vague descriptions, by contrast, invite deeper probing.

When to Consider a Voluntary Disclosure or Amended Claim

If a review reveals that a past allocation was overstated, a full ITC claimed on an input that was really 85% commercial, or an SR&ED salary claimed at full value when the eligible proportion was below 90%, the taxpayer should consider correcting the error proactively. An amended return or claim or, where the circumstances warrant, an application under the CRA’s Voluntary Disclosures Program, can reduce exposure to penalties and demonstrate good faith. Eligibility for the Voluntary Disclosures Program is subject to the CRA’s conditions, including that the disclosure generally be voluntary (made before the CRA has initiated enforcement action).

The decision turns on the size and nature of the error and whether the CRA has already begun enquiries, which makes early legal advice valuable.

Common Pitfalls, Red Flags and 2026 Canadian Tax Changes to Watch

Certain patterns reliably attract CRA attention. Understanding the red flags lets finance teams self-correct before an auditor does it for them.

Common triggers include bulk invoices allocated to commercial use with no supporting detail, missing or reconstructed time records, mid-year reclassifications that conveniently improve a claim, and allocations expressed in suspiciously round figures that land just above 90%. Each of these can signal to the CRA that the reported proportion may not reflect reality.

How Small Clerical Errors Become Substantive Issues

Because the 90% rule canada tax threshold operates near a cliff edge, a minor record-keeping lapse can have an outsized effect. An employee who forgot to log 15 hours of maintenance work against an otherwise experimental project can, once those hours are added back during an audit, drop the eligible proportion below 90% and cost the company full-salary SR&ED treatment. Similarly, a handful of personal trips omitted from a vehicle log can push commercial use under the line and trigger ITC apportionment. What begins as a clerical oversight can become a substantive reassessment.

Best Immediate Remediation Steps

If you discover a potential problem, an unsupported allocation, a missing log, a borderline percentage, act promptly. Reconstruct the best available contemporaneous evidence, recalculate the allocation honestly, quantify the exposure, and take advice on whether an amended claim or voluntary disclosure is appropriate. On the legislative front, taxpayers should monitor measures published through the Department of Finance Canada and the Canada Gazette, as amendments and notices can shift how the CRA interprets eligibility and apportionment. Note that the SR&ED program has been the subject of recent federal budget proposals affecting expenditure limits and eligible costs; confirm current rules for the relevant claim year.

How a Tax Lawyer Helps: Negotiating With CRA and Appeals

A tax lawyer can add value long before a matter reaches court. Early engagement allows counsel to frame the factual record, select and defend an allocation methodology, and engage directly with the CRA over the proportion in dispute. A focused negotiation typically proceeds along these lines: confirm the facts and the records; identify the precise point of disagreement over the 90% rule canada tax threshold; present the strongest contemporaneous evidence; propose a fair and reasonable allocation; and, where the CRA’s position remains adverse, preserve rights by filing a timely notice of objection.

If the objection does not resolve the matter, the dispute can be appealed to the Tax Court of Canada, where the “all or substantially all” standard is tested on the evidence. Counsel’s role is to ensure the record supports the taxpayer’s allocation and to argue, where the facts permit, that “substantially all” is satisfied. Generally, a notice of objection for income tax must be filed within 90 days of the date of the notice of assessment or reassessment (with limited extension relief available), and specific deadlines apply under the Excise Tax Act for GST/HST, confirm the applicable deadline in each case.

Step-by-Step Checklist and Templates

Use the following checklist to manage the 90% rule canada tax test across the audit lifecycle:

1. Pre-audit. Maintain contemporaneous time sheets and usage logs; draft project descriptions at the outset; build reproducible allocation tables; review any allocation within a few points of 90% for a margin of safety.
2. During audit. Respond to CRA information requests promptly and completely; present contemporaneous evidence first; defend your allocation methodology; consider engaging counsel before conceding any point on the threshold.
3. Post-audit. Review any proposed reassessment carefully; file a notice of objection within the applicable deadline if you disagree; consider an amended claim or voluntary disclosure where an error is found; escalate to the Tax Court of Canada where warranted.

Conclusion

The 90% rule canada tax test is deceptively simple in statement and unforgiving in application. Whether you are claiming SR&ED on an experimental project or recovering GST/HST input tax credits on a mixed-use asset, the “all or substantially all” standard rewards taxpayers who document their allocations contemporaneously and disadvantages those who rely on after-the-fact estimates. In 2026, with continued compliance scrutiny and evolving legislative measures, the margin for error remains narrow. Build defensible records, treat borderline allocations with caution, and consider engaging experienced counsel early, well before a reassessment is finalised, to support your claims and preserve your right to object and appeal.

This article is general information, not legal advice; for a specific allocation review or audit response, obtain professional guidance tailored to your facts.

Sources

1. Canada Revenue Agency, SR&ED Eligibility
2. Department of Justice, Excise Tax Act (consolidated)
3. Department of Justice, Income Tax Act (consolidated)
4. Tax Court of Canada
5. Canada Gazette
6. Department of Finance Canada
7. Law Society of Ontario, Certified Specialists Directory