Rental cash damming
Let your rent pay down your home mortgage
Your rent goes onto your home mortgage, and your rental’s expenses are paid with tax-deductible debt, as long as the strategy is followed. Your cash flow and total borrowing stay the same; more of your debt works for you at tax time.
▶ Watch: rental cash damming explained (add your video)
Rental Cash Damming Estimator
See how putting your rental income toward your home mortgage could affect your payoff timeline. It takes about two minutes, and round numbers are fine.
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Assumptions we used
The numbers you entered are your own. These are the assumptions we added to them, and your custom scenario adjusts each one to your situation.
Your custom scenario: $500 + applicable tax
Your estimate gives you a range. Your custom scenario gives you the full picture. It’s a one-hour consult focused on your results and opportunities, built on your actual numbers, which we confirm on a free discovery call. You’ll see your projected:
- Overall wealth improvement: one number that brings every benefit together
- Tax savings, year by year
- Debt conversion date and mortgage freedom date
- Payment savings, and how much less income you’d need to earn to clear your mortgage
- Sale scenario: what selling your rental could look like, and when
Plus what to check before you start (your lender’s limits and prepayment privileges, and anything in your history that needs a closer look), and a full custom proposal showing how the strategy works for you, ready to share with your accountant.
Your custom scenario shows what’s possible; it isn’t a set of instructions. You can put it in place yourself, but the set-up and tracking are where most of the risk lies, so most people put it in place with support. Westora coordinates with your mortgage professional, financial planner and accountant, and provides the tools to do it properly; we’ll walk you through those options on your custom scenario call.
For illustration only. The range uses the numbers you entered and the assumptions listed above. Results aren't guaranteed and will change if rates, property values, income or tax rules change. This is not advice, an official custom scenario or an offer of credit.
Who it suits
Who it’s for
- Homeowners with a rental property or a rental suite
- Landlords with a mortgage on their home
- Those looking to pay off their home mortgage faster
- People comfortable keeping simple monthly records
Who it’s not for
- Homeowners without a rental property or a rental suite
- Those with less than 20% equity in their home
- Anyone who would rather not carry a line of credit
- People who struggle to keep up with bookkeeping
Case study: a neutral cash flow rental property
An illustrative example, not a real client. For more context, watch the full video above.
Personal mortgage
$400,000 mortgage
4.45% × 25 years
$2,200 a month
5% line of credit rate
Rental income and expenses
$2,000 rent a month
$2,000 expenses a month
$0 left over: it breaks even
Income
$145,000 a year
40.7% estimated marginal tax rate
British Columbia (2026)
Alex’s story
Alex is like a lot of landlords. She works hard, pays her mortgage on time and holds a rental she believes in. The rental pays for itself, but it doesn’t put anything in her pocket, and her own mortgage still has 25 years to go. She wants to get ahead without stretching her budget or taking on more than she’s comfortable with.
So she changes how her money moves, not how much she spends. Each month, her $2,000 of rent goes straight onto her home mortgage, and she borrows the same $2,000 back to pay the rental’s bills. She borrows to pay the interest on that debt, too, as its own transaction. Her monthly budget doesn’t change by a dollar.
What changes is the kind of debt she carries. Bit by bit, the mortgage she pays with after-tax dollars is replaced by tax-deductible debt. Every year at tax time, that interest brings her tax savings, and she puts them back on her mortgage. The savings keep coming each year until her tax-deductible debt is paid off.
Alex’s results
The projections below use the original Ontario tax assumptions. British Columbia projections will differ.
See the numbers
Where her $400,000 mortgage went
Became tax-deductible debt: ~$280,300
- Rent borrowed back for the rental’s expenses
- ~$220,800
- Interest borrowed along the way
- ~$59,500
Paid off for good: ~$179,200
- Principal from her regular payments
- ~$154,900
- Tax savings put on the mortgage
- ~$24,300
After the conversion, Alex keeps making the same $2,200 payment, now toward her tax-deductible debt, plus each year’s tax savings. This example keeps rent and expenses equal; in reality, rising rent would also go onto her mortgage and shorten every timeline.
Year by year
| End of year | Home mortgage, regular payments only | Home mortgage, with rental cash damming | Tax-deductible debt (line of credit) | Tax savings that year |
|---|---|---|---|---|
| 1 | $391,024 | $366,291 | $24,558 | $242 |
| 2 | $381,644 | $330,519 | $50,372 | $788 |
| 3 | $371,842 | $292,565 | $77,507 | $1,361 |
| 4 | $361,598 | $252,300 | $106,030 | $1,963 |
| 5 | $350,894 | $209,590 | $136,012 | $2,597 |
| 6 | $339,708 | $164,293 | $167,529 | $3,263 |
| 7 | $328,019 | $116,257 | $200,657 | $3,963 |
| 8 | $315,804 | $65,324 | $235,481 | $4,699 |
| 9 | $303,040 | $11,326 | $272,086 | $5,472 |
| 10 | $289,701 | $0 | $264,865 | $5,989 |
| 11 | $275,762 | $0 | $245,752 | $5,616 |
| 12 | $261,195 | $0 | $226,086 | $5,191 |
| 13 | $245,974 | $0 | $205,851 | $4,755 |
| 14 | $230,067 | $0 | $185,030 | $4,305 |
| 15 | $213,445 | $0 | $163,606 | $3,843 |
| 16 | $196,074 | $0 | $141,562 | $3,367 |
| 17 | $177,923 | $0 | $118,879 | $2,877 |
| 18 | $158,954 | $0 | $95,540 | $2,374 |
| 19 | $139,132 | $0 | $71,525 | $1,855 |
| 20 | $118,418 | $0 | $46,815 | $1,322 |
| 21 | $96,772 | $0 | $21,389 | $773 |
| 22 | $74,152 | $0 | $0 | $213 |
Her home mortgage is fully replaced 3 months into year 10, when her tax-deductible debt peaks at about $280,300. Tax savings are applied once a year.
How it compares with accelerated payments
Not part of Alex’s story, but a common question: what if you just paid extra each month? Accelerated payments use your own money; rental cash damming doesn’t.
| Approach | Monthly payment | Debt-free in | Paid from your own pocket | Tax savings |
|---|---|---|---|---|
| Regular payments | $2,200 | 25 years | $660,800 | — |
| Rental cash damming | $2,200 | ~22 years | $577,100 | ~$66,800 |
| Accelerated payments | $2,700 | ~17.8 years | $578,400 | — |
| Rental cash damming + accelerated payments | $2,700 | ~16.5 years | $535,200 | ~$42,600 |
Accelerated payments mean an extra $500 a month from your own pocket; rental cash damming on its own uses no extra money. The table’s “paid from your own pocket” difference is slightly more than $79,200 because Alex is debt-free just over 3 years sooner. In every row, the rent covers the rental’s expenses. Assumes rates stay the same and tax savings are applied once a year. Your results depend on your numbers, rates and tax situation; the Rental Cash Damming Estimator gives you a range for yours.
What shapes your results
Every scenario is different. These are the factors that move the numbers most.
- Your rental’s monthly expenses set how much is borrowed back each month, which sets the pace of the conversion.
- Interest rates matter, especially the gap between your mortgage rate and your line of credit rate.
- Your rent: any surplus over the rental’s costs also goes onto your mortgage and shortens every timeline.
- Your tax savings: putting them back on your mortgage each year speeds everything up.
Is it right for you?
Rental cash damming works well for the right people. Here’s what to know before you start.
Structure and execution are what make it hold up with CRA
Interest is only deductible when the borrowed money can be traced directly to the rental. That depends on how your mortgage and accounts are set up from day one, and on how every transaction is handled after that. It’s the part that’s easiest to get wrong, and it’s what our implementation support is built for.
- It’s a long-term strategy. The benefits build over years. It isn’t a get-rich-quick scheme.
- This strategy generally requires at least 20% equity in your home and access to a readvanceable mortgage. Your lender or a licensed mortgage broker of your choice can confirm whether your current setup can support the strategy and explain your options if changes are needed.
- It takes ongoing discipline. Borrowed money is used only for the rental, never for personal spending, and monthly records keep every dollar traceable.
- You’ll carry a growing line of credit. Its balance increases over time and its rate is usually variable, so you should be comfortable with that.
- Your circumstances will change. Interest rates, rent, expenses and your income will move over time, and that can make your results better or worse.
- Results aren’t guaranteed. The examples here are illustrations. Your custom scenario is built on your own circumstances.
How we work
We start with a free conversation, and only go further if there’s something worth doing.
- 1
Book a free strategy call
Tell us a little about your situation, and we’ll set up a free discovery call. If there’s a real opportunity, we’ll show you where. If there isn’t, we’ll tell you that too.
- 2
Your custom scenario: $500 + applicable tax
We model the strategy using your own numbers. Your custom scenario is yours to keep, and you’re under no obligation to go further.
- 3
Your professionals, working together
If you decide to go ahead, our consulting fees cover coordinating your strategy with your mortgage professional, financial planner and accountant, as needed, and giving everyone the tools and trackers to carry it out properly. We’ll discuss these fees when we review your custom scenario together.
- 4
Putting it in place
We support you for a full year as you put the strategy in place and follow the monthly tracking process. You keep your records and share them directly with your tax professional at tax time. We don’t provide tax, investment or lending advice.
About
Meet Dustin Marce
I’m Dustin Marce, the strategy consultant behind Westora Capital Strategies. My background in mortgage financing has given me a close look at how homeowners manage their mortgage payments alongside the costs of owning a rental.
Through Westora, I help homeowners with a rental property or rental suite understand how rental cash damming could fit their situation. I started Westora to help people see what the strategy could accomplish and what it would take to put it into practice.
Dustin Marce
Strategy Consultant
Questions
Is cash damming legal?
Yes. Under paragraph 20(1)(c) of the Income Tax Act, interest is tax-deductible when borrowed money is used to earn income from a business or property, such as a rental, and the CRA’s guidelines are followed. The CRA's guidance in Income Tax Folio S3-F6-C1, Interest Deductibility looks at the current use of the borrowed money. That's why every borrowed dollar must be traceable to an eligible use, and why proper set-up and monthly tracking matter so much. Your accountant confirms how it applies to you.
Do I need a special mortgage?
Yes. Every strategy requires a readvanceable mortgage, and some need a specific product from a specific lender. Which one depends on your personal circumstances; there's no one-size-fits-all. Westora doesn't arrange mortgages. If yours needs restructuring, we’ll explain what’s needed, so you can take it to your lender or mortgage professional.
What does my accountant need to do?
Follow the monthly process and keep your transaction records and account statements. At tax time, give those records to your tax professional so they can determine what interest is deductible and report it on your return.
Can I combine this with other strategies?
Often, yes. If another strategy fits your situation, we’ll walk you through it on your discovery call.
Rental cash damming is a debt conversion strategy.
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