The client
A couple buying a zoned-legal duplex in Peterborough, Ontario, at $430,000 plans to occupy the main unit and rent the second. The municipality's zoning certificate confirms two legal units on the property -- but confirming that took the file only so far.
Purchase price
$430,000
Peterborough
Zoning status
2 legal units, confirmed
Municipal zoning certificate
Second unit's kitchen
Removed, never reinstated
No permanent cooking facility
Assumed second-unit rent
$1,400/month
Never actually creditable
Combined income
$9,200/month
Carries the file alone
The problem
A zoning certificate answers one question: does the municipal bylaw allow two units on this property? It says nothing about whether the second unit is actually, physically a self-contained suite today. This one isn't -- a previous owner removed the kitchen years ago, and it was never reinstalled. No permanent cooking facility means no self-contained unit, and no self-contained unit means no creditable rental income, regardless of what the zoning paperwork says.
Legal and livable are two different questions
- ▸Zoning legality: does the municipal bylaw permit this property to have two units at all -- yes, confirmed
- ▸Physical self-containment: does the second unit actually have its own kitchen, bathroom and entrance today -- no, the kitchen is missing
- ▸A lender and its appraiser need the second one, not just the first, before crediting any rental income at all
The couple had budgeted as if the zoning certificate settled the question. It only settled half of it.
The numbers
Qualifying the file correctly meant treating it as a single-income-stream purchase from the start, a pattern worth checking against broader rental market data before assuming a second unit's income is automatically usable.
| The insured purchase, on the couple's own income alone | Amount |
|---|---|
| Purchase price | $430,000 |
| Minimum down payment (5%) | $21,500 |
| Base mortgage | $408,500 |
| CMHC premium (4.00% at 90.01-95% LTV) | +$16,340 |
| Total insured mortgage | $424,840 |
| Ratio check at the qualifying rate | Figure |
|---|---|
| Minimum qualifying rate on a 4.85% contract rate | 6.85% |
| Payment at the qualifying rate, 25 years | $2,936 |
| GDS (payment + $320 tax + $140 heat) ÷ $9,200 income | 36.9% |
| TDS (GDS numerator + $300 car loan) ÷ $9,200 income | 40.2% |
36.9% GDS and 40.2% TDS clear comfortably on the couple's own income, with the second unit's rent left entirely out of the calculation -- had it been creditable, TDS would have run closer to 32.6%, but that was never a number this file could rely on.
The solution
A mortgage agent licensed under Ontario's Mortgage Brokerages, Lenders and Administrators Act confirmed the second unit's physical condition before letting anyone budget on its rent.
First, walked the property with the appraiser specifically to check the second unit's self-containment, not just its zoning status. The missing kitchen settled the question immediately.
Second, confirmed with the lender that no rental income could be credited until the unit was actually reinstated and inspected as self-contained. A distinction worth understanding through general rental income offset practice, none of which applies to a unit that isn't a suite yet.
Third, re-ran the file on the couple's own income alone, rather than contest an appraiser's finding that was simply correct. The ratios cleared easily without the disputed income at all.
The outcome
The purchase funded insured on the couple's own income, GDS at 36.9% and TDS at 40.2%, with the second unit's future rent left out of the file entirely. The couple never needed it to qualify -- but budgeting as if they had it would have been the wrong plan going in.
Zoning legality and physical self-containment are both required before a lender will credit rental income at all -- meeting one without the other still leaves that income at zero.
What to take from this file
- 01A zoning certificate confirms legal permission for a second unit. It says nothing about whether that unit is physically self-contained today.
- 02No kitchen means no self-contained suite, and no self-contained suite means no creditable rental income, regardless of the zoning paperwork.
- 03Walk the property specifically to check physical self-containment before budgeting on a second unit's rent. Don't rely on zoning status alone.
- 04Qualify a file on income you can actually document today. A future improvement plan is a separate conversation from today's ratios.
Sources
Every regulatory figure in this file traces to one of these primary sources. Client details and anything that varies by lender are illustrative, as flagged below.
- ▸CMHC — Purchase (Mortgage Loan Insurance) — default-insurance premium schedule by LTV band (25-year amortization).
- ▸CMHC — CMHC Home Start — minimum down payment tiers (5%/10%) and the $1.5M insured price cap.
- ▸OSFI — Minimum qualifying rate for uninsured mortgages — the minimum qualifying rate — greater of contract rate + 2% or 5.25%.
- ▸CMHC — CMHC Reviews Underwriting Criteria — GDS 39% / TDS 44% maximums and the 600 credit-score floor for insured files.
- ▸Provincial/territorial mortgage-broker legislation fetched directly (bclaws.gov.bc.ca, legisquebec.gouv.qc.ca, fcaa.gov.sk.ca, web2.gov.mb.ca, nslegislature.ca, assembly.nl.ca) plus FCNB's own site for NB and CanLII's index for PE — see notes for per-province method — provincial mortgage regulators and licence titles.
Illustrative in this file — lender-specific, not rules:
- ▸4.85% contract rate — rates move daily; not a quote.
- ▸the 50% rent offset used only as a contrast figure — each lender publishes its own rental-income offset or add-back treatment; 50% is illustrative of one common convention, not a universal figure, and moot on this file since no rent was creditable at all.
Authority & provenance
How this case file was built
We publish the origin, the verification method and the reviewer for every case file, so you can judge how far to trust it before you rely on it with a client.
Where it comes from
Derived from files handled by Treadstone’s fulfillment desk and from scenarios contributed by partner brokerages. Names, employers, exact amounts and dates are changed so no client or file is identifiable.
Provenance: Composite — a pattern seen repeatedly on fulfilled files, not a single transaction.
What is verified
Every regulatory figure traces to a primary source listed above and was checked against it on the date shown. The arithmetic is recomputed by machine on every rebuild.
Anything that varies by lender is labelled illustrative rather than stated as a rule.
Who reviewed it
Reviewed for Canadian regulatory accuracy before publication, and re-checked whenever a cited rule changes.
Reviewed by: Nicholas Parson, Treadstone Associates — reviews every case file before publication.
This case file is professional reference material for licensed mortgage professionals. It is not advice to a borrower, and it is not a lender commitment. Insurer rules, qualifying rates and provincial taxes change — confirm the current position with the insurer, regulator or lender before you rely on any figure here in a live file.