Builder Self-Supply HST Calculator, Section 191
You built it to sell and you are renting it instead. The moment the first tenant takes possession, the Act deems you to have sold the building to yourself and charges HST on its full market value. Work out the tax, the rebates that come back, the return it belongs on and what it costs if you missed it.
net HST cost
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How the Self-Supply Is Calculated
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Purpose-Built Rental Rebate Eligibility
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Dates and Deadlines
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Points That Decide the Outcome
What to Do Next
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Disclaimer: This calculator applies section 191 of the Excise Tax Act at the Ontario rate of 13%, the new residential rental property rebate at 36% of the federal portion phased out between $350,000 and $450,000 per unit to a maximum of $6,300, the Ontario rebate at 75% of the provincial portion capped at $24,000 per unit, and the purpose-built rental housing rebate at 100% of both portions where the complex has at least four private apartment units and construction began after 13 September 2023 and before 2031 with substantial completion before 2036. Ontario announced a further enhanced rental property rebate in its 2026 budget which is not modelled here. Whether construction is substantially complete, whether a unit is a private apartment unit, and the fair market value itself are all questions of fact. Subsidised housing, additions, conversions from non-residential use and substantial renovations follow different rules. This page is general information, not tax advice.
What Section 191 Actually Does
A builder who sells a new home charges HST on the sale price. A builder who rents it out instead makes an exempt supply and would otherwise pay no HST at all, having already recovered the tax on every input through credits. Section 191 closes that gap.
When a builder gives possession of a newly built residential complex to a tenant, the Act deems the builder to have sold the complex to itself and to have collected HST on the fair market value at that moment. The tax is real, it goes on your return, and it has to be funded.
The trigger is possession, not a decision. There is no election and no filing that starts it. The moment the first tenant moves in and construction is substantially complete, the self-supply has happened. Builders who discover this months later have already missed a return.
When the Self-Supply Is Triggered
| Situation | Self-Supply |
|---|---|
| Single home or condo unit leased to a tenant | Yes, subsection 191(1) |
| Apartment building, first unit occupied | Yes, subsection 191(3), on the whole building |
| Addition to an existing rental building | Yes, subsection 191(4), on the addition |
| Builder occupies the home as their own residence | Yes, unless the personal use exception applies |
| Home sold to an arm’s length buyer | No, the actual sale is taxed instead |
| Unit sits finished and empty | No, until possession is given |
It Is Charged on Value, Not on Cost
This is the point that catches people. The tax is 13% of the fair market value of the completed complex at first occupancy. A project that cost $3,200,000 and is worth $4,000,000 is taxed on $4,000,000. The developer’s margin is taxed even though nothing has been sold and no cash has come in.
That makes the appraisal the most important document in the file. It should be dated at the self-supply date and prepared by a qualified appraiser. A value derived from cost, from an asking price or from an appraisal done a year later is the first thing a CRA auditor challenges, and the burden of supporting it sits with you.
The Rebates, and Why They Now Differ Enormously
Two separate rebate streams exist, and which one you fall into can be the difference between paying nothing and paying hundreds of thousands.
| Rebate | Federal Portion | Ontario Portion | Applies To |
|---|---|---|---|
| New residential rental property rebate | 36% of the 5%, phased out between $350,000 and $450,000 per unit, maximum $6,300 | 75% of the 8%, capped at $24,000 per unit | Condos, single units, duplexes, triplexes, and anything outside the window below |
| Purpose-built rental housing rebate | 100% of the 5%, no phase-out | 100% of the 8% | Multiple unit buildings of at least four private apartment units |
On a $4,000,000 eight-unit apartment building the difference is $328,000. As a qualifying purpose-built rental project the rebates return the entire $520,000 of self-supply tax and the net cost is nil. As eight condominium units at the same value, the federal rebate is fully phased out and only $192,000 comes back.
Purpose-Built Rental Eligibility
- At least four private apartment units, each with a private kitchen, bathroom and living area, or at least ten private rooms or suites.
- Ninety per cent or more of the units held for long-term residential rental.
- Construction began after 13 September 2023 and before 2031, with substantial completion before 2036 in Ontario.
- The units must otherwise qualify for the new residential rental property rebate.
- Conversions from non-residential use, such as an office building turned into apartments, can qualify.
- Excluded entirely: condominium units, single unit housing, duplexes, triplexes and substantial renovations.
Ontario mirrors the federal rebate and gives back the full provincial portion on the same projects. Ontario also announced a further enhanced rental property rebate in its 2026 budget, giving up to $80,000 per unit of provincial relief on eligible units. Because the eligibility window for that one is date-sensitive, it needs testing against your specific project rather than assuming.
Which Return It Goes On
The self-supply tax is reported as tax collected on the GST/HST return for the reporting period in which the tax became payable, being the period containing the first occupancy. The rebate is claimed separately on Form GST524.
The rebate application has its own deadline: two years after the end of the month in which the self-supply occurred. Missing it loses the rebate permanently while leaving the tax payable, which is the single most expensive administrative error in this area.
Input Tax Credits, Before and After
| Period | Input Tax Credits |
|---|---|
| During construction, intending to sell or rent | Claimable in full on materials, trades and professional fees |
| At the self-supply | Not clawed back. The deemed sale is a taxable supply, which is what justifies the credits already taken. |
| After the self-supply | Not claimable. Residential rent is exempt, so credits on operating costs stop. |
| Claimed after the self-supply in error | Repayable, with interest |
If You Missed It in a Prior Year
This is common. A builder finishes a project in a soft market, rents the units rather than dropping the price, and nobody tells them a taxable event just happened. The return goes in without the self-supply, and the problem sits there growing interest.
The CRA finds these through occupancy dates, land registry records and rental listings, and builder audits routinely start there. A voluntary disclosure made before the CRA raises the issue removes the penalties entirely and most of the interest. Once an audit begins, that option closes.
What This Calculator Does Not Cover
- Subsidised housing under section 191.1, which has its own deemed value floor
- Substantial renovations, which are excluded from the purpose-built rental rebate
- The section 191(5) personal use exception for an individual builder
- Change of use back to sale, and the credit that can arise on a later taxable sale
- Land transfer tax and municipal charges, which are separate
- Provinces other than Ontario, which have different rates and different provincial rebates
The appraisal and the return date are the whole engagement. Get the value supported at the right date, put the tax on the right return, and file the rebate inside its window. Our service for property developers and builders covers the self-supply calculation, the rebate application and the disclosure where a prior period was missed.
Frequently Asked Questions
Common questions from builders renting out new construction.
Related Calculators and Guides
More tools for Ontario builders and developers.
The Tax and the Rebate Are Two Separate Filings
Send us the occupancy dates, the appraisal and your reporting period. We calculate the self-supply, put it on the correct return, file the rebate inside its window, and prepare a disclosure where an earlier period was missed.