"Rental income" gets used as one phrase, but it describes two genuinely different situations. A subject-property rental is income from the property the borrower is buying right now — it doesn't exist on paper yet, because the borrower doesn't own the property yet. An existing rental is income from a property the borrower already owns, with a real history behind it: a filed tax return, a signed lease, an actual bank deposit pattern.
New agents often treat these as interchangeable because the end result — a rent figure feeding into a ratio calculation — looks the same on the worksheet. The path to get that figure, and how much an underwriter trusts it, is not the same at all.
Since there's no history to point to, lenders lean on the purchase agreement together with an appraiser's opinion of achievable market rent — a formal rental analysis included as part of the appraisal when a lender orders one for an investment purchase, or for a suite in a property the borrower will occupy. That appraisal opinion is covered in depth in Module 05, because how well a broker understands it directly affects how strong a subject-property file looks on paper.
If there's already a tenant in place at closing — say, an existing lease the seller assigns to the buyer — a signed lease can sometimes supplement or replace the appraisal opinion. But for a vacant property or new construction with no tenant yet, the appraisal is usually the only evidence available.
For a property the borrower already owns, two documents do most of the work: the borrower's most recent T776 (Statement of Real Estate Rentals, filed with their tax return), or a current lease agreement together with proof of deposit. Each has a different character. A T776 is backward-looking — it reflects a full year including any vacancy or repair costs that actually happened, which makes it conservative but sometimes stale if the borrower has since re-rented at a higher rate. A lease reflects the current market reality but hasn't been tested by a full year of actual ownership yet.
For a subject property, the underwriter is ultimately trusting an appraiser's professional opinion — which puts more weight on the quality of the comparables the appraiser used and how well they support the estimated rent. For an existing rental, the underwriter is trusting the borrower's own bookkeeping — which puts more weight on whether the T776 or lease figures line up cleanly with the mortgage statement and property tax bill for that specific address. Knowing which kind of scrutiny applies helps a broker anticipate exactly what an underwriter is likely to ask for next.
It's common for both categories to show up in the same application — a client who already owns one tenanted property and is now purchasing a second. The underwriter treats each on its own terms: the existing property through its T776 or lease, the new subject property through its appraisal, before rolling both results into the borrower's overall debt-service picture. That rolling-up process is exactly where portfolio math (Module 09) starts to matter, and it's also where the double-counting error covered in Module 05 most often creeps in.
A client already owns a rental condo they've had tenanted for three years and is now purchasing a second investment property. Which document would a lender typically rely on for the condo they already own?
Existing rentals have a track record, so the file leans on the borrower's own filed tax return or current lease rather than a fresh appraisal — the appraisal route is reserved for the subject property being purchased right now, which has no history yet. The "can never be used" option is the trap for an agent who's heard that portfolio lending gets stricter and wrongly concludes existing rentals stop counting altogether — they absolutely count, they're just documented differently than a brand-new purchase.
