The client
A buyer in Petawawa used a $398,000 purchase-plus-improvements mortgage, with a $42,000 holdback earmarked to convert an unfinished basement into a legal secondary suite -- qualifying entirely on their own $8,700/month income, since the suite the improvement money was about to create did not exist yet.
Purchase price
$398,000, Petawawa
10% down, insured
Improvement holdback
$42,000
Funds a new basement secondary suite conversion
Buyer's own income
$8,700/month
Relied on alone; the future suite's rent is not counted
Other debt
$230/mo car loan
The problem
A purchase-plus-improvements mortgage lets a buyer finance renovation costs into the purchase itself, with the holdback released against inspected, completed work. What it does not do is let a buyer count the income a renovation is going to produce before that renovation exists.
What the file could not count yet
- ▸The basement conversion into a legal secondary suite had not started; there was no suite, no tenant, and no lease
- ▸A projected $1,350/month rent existed only as a market estimate -- not an appraised, leased, or documented figure
- ▸No lender's income calculation has a field for a rental unit that does not yet physically exist
The buyer had budgeted around the future rent from the day the offer went in. The file itself could not.
The numbers
Qualifying the file on the buyer's own income alone, with the improvement money treated as financing for a renovation rather than a future income property, was the only version of the math a lender would actually underwrite at this closing.
| Qualifying without the suite | Amount |
|---|---|
| As-improved lending value (purchase + holdback) | $440,000 |
| CMHC premium (3.10% at 90% LTV) | +$12,276 |
| Total insured mortgage | $408,276 |
| Total debt service | Figure |
|---|---|
| Payment at the qualifying rate (6.95%), 25 years | $2,847/mo |
| Property tax | $340/mo |
| Heat (lender estimate) | $130/mo |
| Car loan | $230/mo |
| Total debt service, buyer's own income alone | 40.8% |
40.8% clears comfortably below CMHC's 44% ceiling on the buyer's own income, with nothing at all credited for the suite that is coming. Once the conversion is complete and a fresh appraisal confirms the unit is legally rentable, one lender's own 50% future add-back convention would add $675/month to qualifying income, moving GDS from 38.1% down to 35.4% -- a change consistent with the kind of shift rental vacancy rate data suggests is realistic for a well-located secondary suite, but it is a later-refinance number, not part of this purchase's own math.
The solution
A mortgage agent licensed under Ontario's Mortgage Brokerages, Lenders and Administrators Act structured the file around what a purchase-plus-improvements program can actually finance now, not what the finished basement will eventually earn.
First, separated the renovation budget from the income question entirely. The $42,000 holdback is financing construction, full stop -- it does not, on its own, create qualifying income at this closing.
Second, structured the draw schedule against inspected, completed work. The holdback releases in stages as the conversion progresses, keeping the lender's security tied to verified progress rather than a promised outcome.
Third, set expectations with the buyer up front about which of the standard rental income offset methods would eventually apply. The $1,350/month rent becomes eligible for qualifying purposes only once the suite is built, inspected, and re-appraised as a legal secondary suite -- and only at a later refinance, not retroactively on this purchase.
The outcome
The purchase funded insured at 40.8% total debt service on the buyer's own income alone, with the $42,000 improvement holdback released against completed, inspected work.
Because this file is CMHC-insured, the 40.8% TDS figure is measured against the real 44% ceiling; the 35.4% figure that appears once the suite's future rent is added is a later-refinance projection, not a number this file needed to satisfy.
What to take from this file
- 01A rental unit that does not exist yet cannot be counted as rental income. A purchase-plus-improvements mortgage finances the renovation; it does not advance-credit the income the renovation will eventually produce.
- 02Separate the construction budget from the qualifying-income question from the start. Treating the holdback as financing for a future asset, not a source of current income, keeps client expectations aligned with what the file can actually do today.
- 03An add-back convention only ever applies to real, appraised rent. A projected figure from before the suite exists is a budgeting estimate, not a number any lender's own add-back or offset policy was built to use.
- 04Plan the second step -- the refinance -- before the first one closes. Telling the buyer up front that the suite's income arrives at a later refinance, once it is built and re-appraised, turns a two-step process into an expected plan rather than a surprise.
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:
- ▸4.95% contract rate — rates move daily; not a quote.
- ▸the 50% future add-back convention — each lender publishes its own treatment for a newly-completed secondary suite; there is no universal rule.
- ▸the $1,350/month projected suite rent — a projected rent for a unit that does not yet exist is an estimate, not an appraised or leased figure.
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.