Most Canadian e-commerce sellers know the CAD $30,000 small supplier threshold exists. Fewer know exactly when the registration obligation starts, how many days they have to act once it does, and what happens to sales made in the gap between crossing the threshold and completing registration. Those timing details, not the existence of the threshold itself, are where sellers most often get the compliance wrong.
GST/HST for Multi-Platform Canadian E-Commerce Sellers covers how the threshold counts revenue across every sales channel combined. This guide focuses specifically on the mechanics of timing: the two tests that can trigger the obligation, the registration deadline once triggered, the effective date of registration, and the separate timing decision behind voluntary registration.
The Two Threshold Tests
CRA’s small supplier rules apply two separate tests, and a seller only needs to trip one of them to lose small supplier status.
The single calendar quarter test. If total taxable revenues from all commercial activity, across every platform, exceed CAD $30,000 in a single calendar quarter, small supplier status ends immediately in that quarter, not at year-end.
The four consecutive calendar quarters test. If total taxable revenues exceed CAD $30,000 across the four calendar quarters immediately preceding the current quarter (regardless of how it breaks down quarter by quarter), small supplier status also ends.
These two tests run independently. A seller can fail the four-quarter test in a quarter where they had comparatively low revenue, because the trailing twelve months add up past CAD $30,000 even though no single quarter did. Sellers who check only their most recent quarter’s revenue against the threshold, without checking the trailing four-quarter total, can miss the point where they crossed.
What Starts the Clock
The registration obligation does not begin on the date a seller decides to register, or the date the registration is filed. It begins on the date the threshold test is failed, meaning the specific transaction that pushes cumulative revenue over CAD $30,000 in whichever test applies.
Once that date is identified, CRA’s registration rules require the application for a GST/HST account to be made without delay, and in practice this is generally understood as needing to register within 29 days of the day the small supplier threshold is exceeded. Missing this window does not eliminate the underlying tax obligation. It just means the seller is now operating as an unregistered person who should have been registered, with the GST/HST collection obligation running from the point the threshold was actually crossed, not from whenever registration eventually happens.
The Gap Between Crossing and Registering
This is the part sellers most often get wrong. Once the threshold is crossed, the seller is required to start charging GST/HST on taxable supplies made in Canada from that point forward, even before the registration application is filed and a GST/HST number is issued.
In practice, most sellers cannot charge GST/HST at checkout the same day they realize they have crossed the threshold. Platform tax settings, Shopify configuration, and invoice templates all need to be updated, and that update typically happens once the registration number is in hand. The result is a gap where GST/HST should have been charged but was not, because the seller had not yet registered or updated systems.
That gap does not erase the liability. The seller who was required to collect GST/HST during the gap period still owes the CRA the tax that should have been collected on those sales, generally out of the seller’s own margin rather than from the customer after the fact, since re-billing customers retroactively for tax on completed transactions is rarely practical. This is the direct cost of registering late: not a penalty from CRA on the registration itself, but an unrecovered tax liability on every sale made in the gap.
Effective Date of Registration
When a GST/HST registration application is filed after the threshold has already been crossed, CRA generally sets the effective date of registration back to the date the small supplier threshold was exceeded, not the date the application was submitted or approved. This retroactive effective date is what creates the exposure described above: the seller is treated as registered, and therefore obligated to have collected GST/HST, from the earlier date, regardless of when the paperwork caught up.
Sellers who track their cumulative revenue closely enough to register proactively, in the same quarter they expect to cross the threshold rather than after the fact, avoid this retroactive gap entirely. That is the practical argument for registering slightly early rather than waiting for a hard confirmation that the threshold has already been passed.
Voluntary Registration: A Different Timing Decision
Sellers under the CAD $30,000 threshold can register voluntarily, and the timing decision here is economic rather than compliance-driven. Voluntary registration opens access to input tax credits on GST/HST paid on platform fees, advertising spend, shipping supplies, and other business costs, at the cost of now having to charge GST/HST on sales and file returns on a regular schedule.
For a new seller with meaningful upfront costs (inventory purchases, initial advertising spend, tooling or software carrying GST/HST) registering voluntarily before the mandatory threshold is reached can recover tax that would otherwise be a sunk cost. The tradeoff is administrative: voluntary registration commits the seller to ongoing filing even in a period where revenue may still be below CAD $30,000, and reversing a voluntary registration back to small supplier status has its own rules and is not something to plan around lightly.
This decision should be made looking at actual projected fee and cost volumes for the specific business, not as a default recommendation to register early in every case.
Filing Frequency After Registration
Once registered, CRA assigns a filing frequency based on annual taxable revenue: annual, quarterly, or monthly, with the ability to elect a more frequent filing period than the assigned minimum. New registrants without a full prior year of revenue on file are typically assigned based on their reasonable estimate of first-year revenue. CRA’s GST/HST filing information covers how the assigned frequency is determined and how to request a change.
Common Timing Mistakes
Checking only the current quarter, not the trailing four quarters. A seller can fail the four-consecutive-quarter test without any single quarter looking alarming on its own.
Treating registration date as the trigger date. The obligation to collect GST/HST starts on the date the threshold was actually crossed, which is often weeks before the registration is filed or approved.
Waiting for a clear signal before registering. By the time cumulative revenue is unmistakably over CAD $30,000, the gap period described above has likely already started. Tracking revenue against the threshold monthly, not annually at tax time, is what prevents this.
Assuming platform-collected GST/HST covers the gap. On marketplaces where the platform is the deemed supplier for unregistered sellers, the platform’s collection responsibility changes once the seller registers. A seller who registers but does not update platform tax settings can end up with a period where neither the seller nor the platform is correctly collecting and remitting.
Registering voluntarily without checking cost volumes. Voluntary registration below the threshold makes sense when there is meaningful GST/HST-bearing cost to recover through ITCs. Registering voluntarily with minimal recoverable cost adds a filing obligation without a matching benefit.
Related Guides
- GST/HST for Multi-Platform Canadian E-Commerce Sellers covers how the threshold counts revenue across every sales channel and how registration changes tax handling on each platform.
- GST/HST for Canadian Amazon Sellers covers the marketplace-facilitator mechanics specific to Amazon before and after a seller registers.
- GST/HST Input Tax Credits for E-Commerce Sellers covers what becomes recoverable once registered, which is the core economic case for voluntary registration.
Scope of This Guide
This guide covers the timing mechanics of GST/HST small supplier status and registration for Canadian e-commerce sellers. It does not cover:
- Quebec QST registration, which follows a separate process administered by Revenu Québec
- Provincial sales taxes (BC PST, Saskatchewan PST, Manitoba RST), which have their own thresholds and timing rules
- Full return preparation and remittance mechanics once registered
- Deregistration back to small supplier status
The authoritative source is the CRA’s GST/HST registration guidance.
If you are approaching CAD $30,000 in combined revenue across your sales channels and are not sure exactly when your registration obligation starts, that timing question is worth resolving before the threshold is crossed, not after.
Get in touch to review where your revenue stands against the threshold.