Canada's 6.4% Productivity Mega Deduction vs US Tariffs: the 2026 cross-border tax math

What the Productivity Mega Deduction actually is

Prime Minister Mark Carney announced the Productivity Mega Deduction at the Canada Investment Summit in Toronto on September 15, 2026. It is a proposal, not law: the Department of Finance backgrounder says the government “proposes to implement” it, and tax practitioners have been blunt — “It should not, however, be treated as enacted law.” The measure would extend immediate expensing, a full write-off in the year an asset is bought, to a much wider set of capital assets. Finance Canada's own number is that “about two-thirds of investment in capital assets would be eligible”, up from roughly 15% today.

The three-step METR sequence

The 13% that the proposal cuts from is itself recent, which is why a comparison that starts in 2024 understates the change:

What is eligible, and what is not

Eligible: depreciable machinery, equipment and other capital assets used in a business, covering roughly two-thirds of capital investment on Finance's estimate. Excluded: CCA Class 1 and Class 3 buildings, Class 14.1 property such as goodwill, franchises and quota, Class 51 pipelines, property described in Schedule V and Schedule VI, and Class 10 and 10.1 passenger vehicles that were previously used or assembled outside Canada. Assets outside the deduction are not left with nothing: “Assets not eligible for immediate expensing will continue to receive an enhanced first-year deduction under the Accelerated Investment Incentive.”

That is where the headline rate comes from. Finance Canada models the marginal effective tax rate on new business investment, which it defines as “the tax imposed on an additional dollar of business investment”, and says the rate “will fall from roughly 13% to 6.4%” — “a massive 10.5 percentage points below the U.S.” on TD Economics' reading. The department calls the result the lowest rate of any major economy. The measure's price tag is Finance's own: “The estimated incremental fiscal cost of the measure is $36 billion over five years, beginning in 2026-27”, roughly $8.5 billion a year on average. For the tariff chronology this page does not duplicate, start with the US–Canada tariff picture.

The US duty stack on Canadian equipment in 2026

Three different US instruments get folded together in coverage of this story. Only one of them is a duty on general Canadian machinery, and the ceiling on the others is what makes the mix-up expensive.

Section 301 forced-labor duties

The duty that lands on Canadian machinery is the Section 301 forced-labor action. The Federal Register notice states that the Trade Representative “has determined to impose 10 percent tariffs on products of Canada, except as provided in Annex I and Annex II, Part A, of this Notice.” The president's memorandum puts Canada in the flat 10 percent group, and the action took effect on July 24, 2026. It applies on top of the HTS line's ordinary MFN rate. For most Chapter 84 machinery that MFN rate sits near zero, but it is a line-by-line input you supply, not a rate this page can assume for your goods. The Section 301 forced-labor action covers 54 economies.

Why Section 338 is not the one you want

Section 338 is the loudest of the three and the least relevant to equipment. It is an authority with a hard ceiling — 19 U.S.C. § 1338 permits duties “not to exceed 50 per centum ad valorem” — and it was used for the first time in July 2026 against motor vehicles, alcoholic beverages and dairy: “The proclamations target motor vehicles, alcoholic beverages, and dairy products”. General machinery is not in that scope, and no version of the September 2026 instruments adds it. The September 8, 2026 proclamations added three import bans effective September 29, 2026 and two scope modifications effective September 15; those are the dates on the September 15 and September 29 Section 338 dates. If the machine carries steel or aluminium content there is a second layer — Section 232 metals duties — and the forced-labor action excludes “products already subject to sectoral tariffs under Section 232 of the Trade Expansion Act”, such as articles of steel and aluminium. Section 338 duties, where they bite, stack on top: “shall apply in addition to duties imposed pursuant to Section 232”.

Why the duty number and the tax-rate number cannot be added

A 10% duty is a one-time charge on the purchase price. A 6.4% METR is a rate applied to the return from an investment, every year. They are different units, and adding them produces a number that describes nothing. The arithmetic makes the gap plain. On a $2,000,000 machine entered without USMCA origin, the Section 301 duty is $200,000 once. The Canadian advantage over the United States in the same year, measured on a $100,000 pre-tax return, is $10,500 — the difference between 6.4% and 16.9% applied to that return. It takes 19.05 years, undiscounted, for the annual tax difference to equal the one-time duty.

Change the return assumption, the holding period or the origin status and both numbers move. How a duty number is built covers valuation and stacking on the border side. The Canadian half of the same trade runs the other way: Canada’s counter-tariffs on about US$20 billion, or C$27.6 billion, of US goods at 15 to 50 percent, effective September 8, 2026 — a third charge, paid by a different party.

Worked example: a $1,000,000 equipment purchase, three ways

Take one machine, $1,000,000, bought for a Canadian operation. Three separate calculations apply to it, and each one uses different inputs. The first is a border charge, the second is a rate on the return, and the third is a timing effect inside the tax return.

The calculator on this site has four modes — duty, TRQ, Section 338 and copper. None of them computes this deduction or a marginal effective tax rate, and this page does not claim they do. Run the duty leg through open the tariff calculator, and treat the two tables below as the other half of the decision.

The only gate that connects the two: USMCA origin

One sentence in the Federal Register is the hinge of this whole comparison. The additional duties imposed by heading 9903.05.29 “shall not apply to any products of Canada entered free of duty under the United States-Mexico-Canada Agreement”. Read it precisely, because the two sides of this page meet nowhere else. The 6.4% is available to a Canadian operation whatever its inputs; the 10% duty turns on whether the specific good qualifies as originating and is entered free of duty under USMCA. That is a product-by-product test on tariff shift and regional value content, not a country label, and the USMCA origin test walks the qualification rules.

Two boundaries are worth stating next to that sentence. First, USMCA does not reduce Section 232 metals duties: steel and aluminium content can carry 50 percent exposure even on a machine that qualifies as originating. Second, if duty has already been paid, tariff drawback is the recovery mechanism for goods later exported or used in a qualifying way, and the 2026 exemption list is where the exclusion mechanics sit. The Annex product lists themselves are not reproduced on this page. The rule is quoted from the notice body, but the Annex tables did not survive text extraction from the filed documents, so no specific exempt HTS line is presented here as fact.

Sector by sector: where 6.4% is misleading

6.4% is an economy-wide rate and no single industry faces it. Finance Canada's own sector chart runs from -6.0% in agriculture and fishing to 19.3% in retail, and a negative METR means the tax system subsidises the marginal investment rather than taxing it. Manufacturing and processing — the sector most likely to be buying the machine in the example above — is modelled at -1.2% in Canada against 11.1% in the United States. The US figures in that chart are Finance Canada's 2026 estimates, not US Treasury numbers, and Finance “does not separately publish a mining-sector METR”, which is why 6.4% must never be quoted as the rate facing any one industry.

What this does not do

Three limits belong next to the arithmetic. First, the US cost-recovery regime is not the weaker one on machinery. The Tax Foundation's reading is that the United States “made full expensing permanent for machinery and equipment”, and is “currently offering a broader expensing regime than Canada” — so the 6.4% headline is a modelled METR comparison, and it is not a settled conclusion that a dollar invested in Canada beats a dollar invested in the United States for every asset class. Second, immediate expensing “is a tax deduction, not a government reimbursement or cash grant”. It moves a deduction that already existed into year one; it is not a government reimbursement, and a company with no taxable income to reduce gets no year-one cash from it. Third, the measure is a proposal. Until legislation is tabled and receives royal assent, the 6.4% describes what Finance has announced it intends to do.

The 6.4% also does nothing on the border. It cannot reduce a duty, change a landed cost, or alter the origin test. Those are the two legs of a cross-border capital decision, and they are counted in different units on different dates by different governments.

Frequently asked questions

Sources and method (read 18 September 2026): the METRs are Finance Canada's published marginal effective tax rates on new business investment, and the duty figures are the published Section 301 and Section 232 action rates and the Section 338 ceiling. The dollar amounts in the worked example are arithmetic on those published rates (scripts/tax_model.py, Decimal) and are labelled as arithmetic wherever a return assumption is involved. This is not tax or customs advice, and it is not a prediction.
Accuracy note. The measure is announced and proposed: as of 18 September 2026 no bill has received royal assent, so no rate here should be applied as law. No search volume, impression or rank position is stated anywhere on this page. The Annex product lists referenced by the Section 301 notice are not enumerated, because the Annex tables did not survive text extraction from the filed documents. Finance Canada's release was read through an archived copy taken 18 September 2026; the live canada.ca host was unreachable from this environment.
Last updated: 18 September 2026 — first edition, written against the September 15, 2026 announcement.

Source list:
• Office of the Prime Minister — Prime Minister Carney introduces the new Productivity Mega Deduction, 15 September 2026 (the 13% to 6.4% move; the G7 framing)
• Department of Finance Canada — release and backgrounder, September 2026 (archived copy read 18 September 2026: Chart 1 and Chart 2 METRs, eligibility, the $36 billion cost)
• Federal Register 2026-15274 — presidential memorandum, Section 301 forced-labor action (10 percent tariff rate: Canada)
• Federal Register 2026-15181 — USTR notice of actions (the 10 percent rate on products of Canada; the USMCA carve-out under heading 9903.05.29)
• Federal Register 2026-14997 — Section 338 proclamation on Canadian products
• 19 U.S.C. § 1338 — the Section 338 authority and its 50 per centum ceiling
• TD Economics on the Productivity Mega Deduction (the 10.5 percentage point gap to the United States)
• Tax Foundation — the counter-case: the US made full expensing permanent for machinery and equipment
• The Deep Dive — immediate expensing described as a deduction rather than a grant; no mining-sector METR published
• Umma Tax Law — proposal status and eligibility detail
• Gowling WLG — the 13% to 6.4% sequence described as a proposal
• Osler — the change described as applying once enacted
• BLG — the Budget 2025 step from 15.4 per cent to 13 per cent, and the further move to 6.4 per cent
• Morrison Foerster — the Section 338 revival and its product scope
• ALS — the five September 8, 2026 proclamations and how Section 338 stacks with Section 232
• Baker McKenzie — the 10 to 12.5 percent Section 301 country split, the July 24 effective date, and the Section 232 exclusion
• TaxTips.ca — 2026 corporate income tax rates (the 26.5% combined federal–Ontario general rate used as an input)
• Canada’s National Observer — the $36 billion / five-year cost framing

More 2026 duty and trade analysis: the tariff advisory desk.