Architects with US projects: treaty cover, state lines, and the licence behind the fee

The fee: W-8BEN-E up front, Article VII underneath

Fees for design work performed at your Ontario office are not US-source income, and under Article VII of the Canada–US treaty the US cannot tax your firm's business profits without a US permanent establishment. US procurement teams still default to demanding a W-9 and threatening 30 percent withholding; the answer is a completed W-8BEN-E for the corporation, kept current — it lapses at the end of the third calendar year after signature. Bill in USD, book at the rate when earned, and treat the collection difference as FX, not a fee adjustment.

For firms with recurring US work we add a protective Form 1120-F with a Form 8833 treaty disclosure each year. Filed on time, it preserves the right to deductions if the IRS ever argues a US trade or business existed, and it avoids the $10,000 corporate penalty for an undisclosed treaty position. It is a thin return, and cheap insurance against a gross-basis assessment.

The licence and the firm both have to exist in the state

Before tax, there is practice law: sealing drawings for a US project requires an architect licensed in that state, and many state boards register the firm as well as the individual — NCARB certification is the usual bridge for OAA-licensed architects. Qualifying to practise usually also means qualifying the corporation with the state's business registry, and a registered firm is an easy match for the state's tax department. So the tax registrations should follow in the same breath: income or franchise tax where required, and payroll withholding for anyone working in-state.

The point that surprises firms: states are not bound by the treaty. A firm with zero US federal tax can still owe state income or franchise tax once its people work in-state regularly. State thresholds are lower, and they do not wait for 183 days.

Contract administration is a day count

Design happens in Toronto; the CA phase happens on site. The treaty's services PE rule makes profits taxable once your firm provides services in the US for 183 days or more in any twelve-month period on the same or connected projects — and the days of every partner, associate, and technologist on that project count together. A monthly site review will not get there; a resident site architect through construction will. We keep a per-project US day register and flag the trajectory quarters ahead, because restructuring the CA arrangement works before the count runs out, not after.

Architect is a TN (USMCA) profession — a degree or a provincial licence supports working entry — so moving people legally is rarely the obstacle. The obstacle is what their days do to the firm's position, and to their own: an employee spending a season in one state can trigger state payroll withholding even while the firm stays federally protected.

The mirror image: US consultants on your Canadian jobs

Cross-border runs both directions. When you bring a US engineer, lighting designer, or specialist consultant onto a Canadian project and any of their work happens in Canada, Regulation 105 requires you to withhold 15 percent from the fee and report it on a T4A-NR — and the liability is yours if you miss it, not theirs. Work performed entirely from their US office needs no withholding. Consultants can apply for a treaty-based waiver when Canada would ultimately tax nothing, but the waiver must be in hand before you pay, so it belongs in the sub-consultant agreement, not the year-end file.

The rest of the Canadian file behaves normally: fees for designing US real property are generally free of HST, while Canadian projects billed to US developers are not — HST follows the property, not the payer. Our architect tax services page covers the T2, the OAA certificate of practice, and the domestic side in full.