Developers Want You to Deduct Mortgage Interest on New Homes: What Ottawa Isn't Being Told

The Canadian Home Builders' Association has advocated for mortgage interest deductibility on newly constructed homes only. Not resales. Not your neighbour's 1987 split-level. Just the house that hasn't been lived in yet.

The pitch sounds like tax relief for first-time buyers stuck at 5.4% renewals when they qualified at 1.79%. The mechanism is different. Tax deductibility lowers your taxable income at year-end, not your monthly payment at the point of qualifying. If you're in a 30% marginal bracket and you paid $18,000 in mortgage interest, you get a $5,400 tax refund. Your bank still made you qualify on the full monthly payment. The refund comes later, once you've already carried the load.

Here's the part the CHBA emphasized to Ottawa: developers need 60% to 80% of units pre-sold before a lender will issue construction financing. If buyers can't afford the mortgages, the projects don't break ground. The association framed this as a supply tool, not a demand subsidy. The government only "pays" when new housing supply actually gets created, because the deduction applies exclusively to units that didn't exist before.

The revenue cost nobody wants to model yet

The United States allowed mortgage interest deductibility on primary residences for decades. By 2017, the Joint Committee on Taxation estimated the federal revenue cost at $66.4 billion USD per year. Canada's housing stock is smaller, but applying even a scaled version of this policy would represent a multi-billion-dollar line item at a time when the deficit is already a political flashpoint. The CHBA proposal does not include a revenue estimate, and the Department of Finance has not released one.

Tax expenditures of this scale get scrutinized. Hard. The usual critique is that deductibility inflates prices by increasing what buyers can afford, which sellers then capture. If every buyer in a bidding war suddenly has an extra $400 per month of effective room in their budget, the winning bid rises by roughly that amount. The net effect is a wealth transfer to existing landowners and developers, funded by taxpayers, with minimal improvement in actual affordability.

That logic assumes a stable supply curve. The CHBA's counter is that supply isn't stable. Construction starts have slowed because developers can't move inventory at current interest rates. In markets like Vancouver West, where detached homes benchmark between $1.78 million and $1.82 million as of August 2026, even buyers with 20% down face monthly carrying costs north of $8,000 at a 5% rate. Very few households qualify. Very few projects pencil.

If the deduction increases the pool of qualified buyers enough to restart stalled projects, you get more units. More units eventually suppress price growth, even if individual transaction prices rise in the short term because buyers are bidding with tax-assisted budgets. The question is whether the supply response is large enough and fast enough to offset the demand-side inflation. Nobody has run that model with Canadian data.

Who this helps and who it doesn't

The proposal only benefits buyers who can already afford a down payment and pass the mortgage stress test at the contract rate. It does nothing for renters who can't assemble $80,000 for a down payment on a $400,000 condo. The tax refund arrives in April, long after you've made twelve months of full payments. If you're living paycheque to paycheque, that timing doesn't solve the cash-flow problem that kept you out of the market in the first place.

Business owners and investors already deduct interest when borrowed funds are used to earn income. The rule requires a reasonable expectation of income, dividends, interest, or rent. A primary residence generates none of those. This proposal would extend a version of that treatment to individuals buying a home to live in, but only if that home is newly built.

The federal government recently removed GST on purpose-built rentals and extended 30-year amortizations to first-time buyers of new builds. Both moves aimed to increase supply. Mortgage interest deductibility would be the third lever in that same toolkit, larger and more expensive than the first two combined.