Who We Help · Engineering Firms · Cross-Border Tax
Engineering firms with US contracts: keep the SR&ED, count the site days
The best-kept fact in this niche: fees from a US client generally do not reduce an engineering firm's SR&ED claim, because contract payments only grind the credit when the payer is resident in Canada or carries on business here. A firm can bill a Texas client for development work and still claim the enhanced refundable credit on qualifying work done in Canada. The real exposure is on site — where treaty day counts and state tax registries run on different clocks.
By the AnalytIQ Accounting team · Last reviewed: August 12, 2026
US contracts and SR&ED stack — if you know the contract-payment rule
The Income Tax Act reduces SR&ED qualified expenditures by contract payments — amounts a client pays you to perform research on its behalf. But the definition only captures payments from a taxable supplier: broadly, a payer resident in Canada or carrying on business in Canada. Fees from a US client with no Canadian footprint sit outside it, which means development work billed to that client can still support a full claim — provided the work itself meets the SR&ED tests and is performed in Canada by your people.
The credit is worth protecting: for a CCPC the enhanced rate is 35 percent, refundable, on up to $6 million of qualifying spend a year — Budget 2025 raised the expenditure limit for taxation years beginning on or after December 16, 2024, and restored capital expenditures to eligibility. We are also honest about scope: most consulting engineering is skilled application of known methods, which is not SR&ED. We claim the projects with genuine technological uncertainty and leave the rest out, because a graded-down claim costs more than it pays — our engineering firm tax services page goes deeper on what survives review.
Billing the US client: W-8BEN-E and the no-PE position
Analysis, modelling, and design performed in your Ontario office are taxable only in Canada under the treaty's business-profits article, as long as the firm has no US permanent establishment. Hand every US client a W-8BEN-E at onboarding so nothing is withheld from fees, and for a firm with recurring US revenue, file the protective US return annually: a foreign corporation that files too late can lose the right to deduct expenses if the IRS ever recharacterizes the position, which converts a tax on profit into a tax on gross revenue.
Site work runs on two clocks: the treaty's and the state's
Commissioning, inspections, and field engineering put your people inside the US, and two systems start counting. Federally, the treaty is patient: a services PE arises only once your firm provides services in the US for 183 days or more in any twelve-month period on the same or connected projects, all staff combined. States are not patient, and they are not bound by the treaty: an engineer stationed at a plant for a season can create payroll-withholding duties and income or franchise tax nexus long before the federal count matters.
Licensure runs on a third clock. Practising engineering in a state generally requires a PE licence in that state — most firms route it through NCEES records — and the licensing registration is often what puts the firm on the state revenue department's radar in the first place. Sequence the tax registrations with the licence, not after the first notice.
| Engagement pattern | Treaty (federal) | State reality |
|---|---|---|
| Modelling and design from Ontario, deliverables sent south | Protected — no PE, W-8BEN-E on file | Nothing, absent people or property in-state |
| Short commissioning trips, a week at a time | Protected while combined days stay low | Usually tolerable; keep a per-state day log |
| Field engineer resident on one project for months | Services-PE risk as the 183-day count builds | Payroll withholding and franchise or income nexus likely |
| US office opened or US-resident staff hired | PE — US filings become real, not protective | Full registration in that state from day one |
The Canadian mechanics: USD WIP and the HST exception that surprises
Long engagements mean unbilled WIP in USD, and FX drift on WIP is why engineering P&Ls look wrong at year-end: milestones book at the rate when earned, collections at the rate when paid, and the gap is FX gain or loss — not project margin. Keep the two separated or your job costing lies to you.
On HST, exported engineering services are generally zero-rated — with one exception that catches firms every year: a service in respect of real property situated in Canada is excluded. Designing an Ontario bridge retrofit or plant upgrade for a US owner still carries 13 percent HST, whoever pays the invoice. Set the tax code by project location, not by client address, and the assessment never accrues.
Source: CRA — Scientific Research and Experimental Development (SR&ED) tax incentive program.
Common questions.
Does billing US clients reduce our SR&ED claim?
Generally no. Contract payments only grind qualified expenditures when the payer is resident in Canada or carries on business here — a US client with no Canadian presence sits outside the rule, so qualifying work performed in Canada still supports the full credit.
Our engineers commission plants in the US. When does that become taxable there?
Federally, at 183 days of services on the same or connected projects in any twelve-month window, counting all staff together. States move sooner — payroll withholding and franchise tax can apply after far less time on site.
Do we charge HST to US clients?
Exported engineering services are generally zero-rated, with one big exception: work in respect of real property situated in Canada carries HST at that province's rate no matter who pays. Code invoices by project location, not client address.
Related reading
US revenue in, credits intact.
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