Treadstone Associates
Case File № 031 · Rental & Investment

The legal duplex that paid for itself

a Saskatoon house-hack at 10% down

Without the secondary suite's rent, a Saskatoon duplex purchase fails GDS at 41.3% on the buyers' income alone. With a lender's 50% suite add-back, the same file clears at 38.1% — insurable at 10% down on an owner-occupied two-unit property.

SaskatchewanInsured · 90% LTVFiled August 7, 20265 min read
41.3%

GDS on the buyers’ income alone — over the 39% cap

38.1%

GDS once the suite’s lease is added at 50% — approved

39/44

CMHC’s maximum GDS / TDS for insured files

Anonymized illustration. The borrowers, dollar figures, and rates in this file are an illustrative composite — no real client is identifiable, and any rate shown is illustrative, not a quote. The rules are real: every regulatory figure is cited to its source in the Sources section, and the math computes exactly as shown.

№ 01

The client

A couple buying a legal duplex in Saskatoon planned to live in one unit and rent the other — a house-hack that has become more common as Canadian rental vacancy stays tight enough that a legal second suite rents itself. On their income alone, the purchase didn’t qualify. With the suite’s lease counted, it did — comfortably.

Borrowers

Couple, both salaried

$104,000/year combined

Purchase

$495,000 legal duplex, Saskatoon

Owner-occupied, one unit already tenanted

Down payment

$49,500 — 10%

Suite lease

$1,450/month, signed

50% add-back is this lender’s published treatment (illustrative)

Other debt

Car payment $480/month

First lender tried

Would not count any suite income

Treatment varies by lender on owner-occupied 2-unit purchases

№ 02

The problem

On the buyers’ income alone, GDS runs to 41.3% — over the 39% insured cap — even with a tenant already in place, because the first lender they tried simply does not count suite income toward qualifying on an owner-occupied 2-unit purchase at high ratio. That is a lender-by-lender choice, not a rule.

The math without the suite

  • P&I at the qualifying rate ($3,074) + property tax ($358) + heat ($150) = $3,582/month in housing costs
  • $3,582 ÷ the buyers’ $8,667 income = 41.3% GDS — over the 39% ceiling
  • Declined at this lender, on the borrowers’ income alone, despite a signed lease already in hand

The frustrating part for the couple was that nothing about their own file had changed between the two lenders — same income, same debts, same signed lease, same legal duplex. What changed was entirely on the lender’s side of the desk: one underwriting workflow is built to read a subject-suite lease as qualifying income, and one simply isn’t, regardless of how well-documented the lease is.

It is also worth naming what did not happen here. Nobody asked the couple to inflate the lease, find a second tenant, or restructure the purchase as an investment property to make the numbers work. The property was already a legal duplex, the lease was already signed at a defensible market rate, and the only lever that moved was which lender’s published policy got to read that lease. That is a narrower, cleaner fix than most credit or income problems allow for, precisely because the underlying facts of the file were never in question.

№ 03

The numbers

At 10% down this is an insured 2-unit owner-occupied purchase, structured through CMHC’s standard bands the same way a single-family purchase would be.

Structuring the insured 2-unit purchaseAmount
Purchase price$495,000
Down payment (10%)−$49,500
Base mortgage (90% LTV)$445,500
CMHC premium — 3.10% in the 85.01–90% LTV band, capitalized+$13,810
Total insured mortgage$459,310
Rate & qualifying paymentFigure
Contract rate (illustrative, not a quote)4.49%
Minimum qualifying rate — greater of contract + 2% and 5.25%6.49%
Monthly P&I at the qualifying rate$3,074

The suite, added to income rather than netted against costs

The mechanic here differs from a rental-offset on a non-subject property (see rental offset): on an owner-occupied subject property, this lender’s published policy is a straight add-back of half the lease to the income side, not a netting against the suite’s own carrying costs.

Qualifying incomeMonthly
Personal income$8,667
+ 50% of the signed suite lease ($1,450 × 50%)$725
Qualifying income used$9,392
GDS / TDS with the suite countedMonthly
Housing costs (unchanged from above)$3,582
$3,582 ÷ $9,392 → GDS 38.1% — under the 39% cap
Car payment$480
$4,062 ÷ $9,392 → TDS 43.2% — under the 44% cap
№ 04

The solution

An FCAA-licensed mortgage associate did three things.

First, diagnosed the decline as a suite-income policy question, not a borrower-quality one — the same signed lease was on the table both times.

Second, matched the file to a lender whose published policy adds 50% of a signed lease to income on an owner-occupied 2-unit purchase (illustrative — every lender and insurer sets its own treatment; the full landscape is mapped in our comparison of rental income offset methods).

Third, backed the lease with a market-rent appraisal addendum, so the lender’s own valuation corroborated the $1,450 figure rather than taking the lease at face value alone.

The order of these steps mattered. Shopping the file to a second lender before confirming why the first one declined would have risked repeating the same mismatch somewhere else; diagnosing the policy gap first meant every subsequent conversation with a lender started from the right question — does your policy count subject-suite income on an owner-occupied purchase, and if so, how — instead of resubmitting the same package and hoping for a different answer.

Signed lease for the secondary suite ($1,450/month)
Market-rent appraisal addendum confirming the suite’s rent is at or near market
Two years of T4s and Notices of Assessment for both borrowers
90-day history of the $49,500 down payment
Purchase agreement and legal-duplex zoning confirmation
Letters of employment
№ 05

The outcome & the margin the suite bought

Funded insured at 10% down, 25-year amortization — the suite carried the entire margin between a 41.3% decline and a 38.1% approval. Saskatchewan’s 6% tax on the $13,810 insurance premium came to $829 in cash at closing, alongside land-title registration fees that were budgeted with legal costs rather than quoted as a fixed figure.

№ 06

What to take from this file

  • 01On an owner-occupied 2-unit purchase, whether suite income counts is entirely a lender policy question. This file swings from a 41.3% decline to a 38.1% approval on that one variable alone.
  • 02A signed lease alone often isn’t enough. A market-rent appraisal addendum lets the lender’s own valuation corroborate the rent being claimed.
  • 03Suite add-backs and rental offsets are different mechanics. One boosts the income side; the other nets against costs on the liability side — know which one a given lender actually uses.
  • 04Saskatchewan is one of three provinces — with Ontario and Quebec — that taxes the default-insurance premium itself. Budget the 6% in cash, separate from the down payment.
  • 05Minimum down payment tiers apply to a legal duplex the same way they apply to a single-family home when it’s owner-occupied. 10% here was a choice, not a requirement.

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.

Illustrative in this file — lender-specific, not rules:

  • 50% suite add-back — subject-suite income treatment varies by lender and insurer.
  • 4.49% contract rate — illustrative, not a quote.

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.

First published 7 August 2026Rules last verified 7 August 2026Next scheduled review 7 February 2027

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.

Treadstone fulfillment

Files like this are daily work for our desk.

Document collection, ratio math under multiple treatments, lender placement notes, and submission-ready packaging — for Canadian mortgage brokers who would rather be in front of clients.