Key Takeaways
- Cash damming converts non-deductible personal mortgage interest into potentially tax-deductible interest for Canadian landlords
- Cash damming relies on section 20(1)(c) of the Income Tax Act, which provides that interest on money borrowed for the purpose of earning income from a business or property may be deductible. Your tax professional can confirm how this applies to your specific situation
- You need a source of rental income, either from a rental property or secondary unit in your home, a primary residence mortgage, and a readvanceable mortgage or HELOC to get started
- Freedom10 clients typically pay off their mortgage 5-12 years faster while saving hundreds of thousands in taxes and interest
What Is Rental Cash Damming?
Cash damming is a tax strategy designed specifically for Canadian landlords who want to accelerate their non-deductible mortgage payoff while reducing their income tax burden. It works by restructuring how you pay for rental expenses so that the interest on your borrowing may become tax-deductible over time.
Here's the core concept: instead of paying your rental property expenses (like rental property mortgage payments, property tax, landlord insurance, maintenance fees, and utility bills) from your rental income, you pay those expenses using a HELOC (Home Equity Line of Credit), preferably secured to your primary residence or second home. Then, you take the rental income that would have paid those expenses and apply it directly to your personal mortgage as a lump-sum prepayment.
The result? Your personal mortgage shrinks faster, and the HELOC interest you're paying on the borrowed funds used for rental expenses may become tax-deductible because the borrowed money was used for the purpose of earning rental income. Your tax professional will confirm the deductibility based on your specific situation.
Why Does Rental Cash Damming Work?
The strategy works because of a fundamental principle in Canadian tax law. Under section 20(1)(c) of the Income Tax Act, interest on money borrowed for the purpose of earning income from a business or property may be deductible.
When you borrow from your HELOC to pay eligible rental expenses, you're using borrowed money for the purpose of earning rental income. That may make the HELOC interest deductible. Meanwhile, you're using the freed-up rental income to pay down your non-deductible personal mortgage faster.
Over time, you're effectively converting non-deductible debt (your personal mortgage) into potentially deductible debt (your HELOC used for rental purposes). The total amount you owe stays roughly the same, but the character of that debt changes in your favour.
A Simple Rental Cash Damming Example
Let's say you have:
- A $500,000 personal mortgage at 5% interest
- A rental property generating $3,000 per month in rental income
- $3,000 per month in total expenses, including the rental property mortgage payment and rental expenses (property tax, insurance, maintenance, utilities)
Without cash damming, you use the $3,000 rental income to cover the $3,000 in rental expenses. Your personal mortgage is paid down only through your regular mortgage payments.
With cash damming, you borrow $3,000 from your HELOC to pay the rental expenses. You take the full $3,000 rental income and apply it as a prepayment to your personal mortgage. That is an extra $3,000 per month going directly to your mortgage principal, converting it into a deductible investment loan and paying it off years faster. And the interest on that $3,000 HELOC draw may be tax-deductible because the borrowed funds were used to earn rental income.
Who Should Consider Rental Cash Damming?
Cash damming is designed for Canadian landlords who meet these criteria:
You own at least one rental property (house, condo, basement suite, or multi-unit) held in your personal name. Properties held in a corporation require a different structure You have a primary residence or second home with a mortgage you want to pay off faster You have (or can get) a readvanceable mortgage or HELOC attached to your home Your rental property generates income (even if cash flow is negative, the strategy can still help) You're in a marginal tax bracket of 25% or higher (the higher your bracket, the bigger the potential tax savings)
How Is Rental Cash Damming Different from the Smith Manoeuvre?
Both strategies convert non-deductible debt into potentially deductible debt, but they work differently:
Cash damming uses rental income and rental expenses to create the conversion. It requires a rental property. The primary goal is accelerated mortgage payoff and tax savings.
The Smith Manoeuvre uses investment contributions instead. You borrow from your HELOC to invest in eligible income-producing assets, which may make the HELOC interest deductible. It doesn't require a rental property. The primary goal is wealth accumulation.
Many Freedom10 clients implement both strategies simultaneously for maximum impact. Learn more in our detailed comparison of cash damming vs the Smith Manoeuvre.
Is Rental Cash Damming Right for You?
Cash damming isn't for everyone. It requires discipline, proper record-keeping, the right mortgage product, and ongoing maintenance for the life of the strategy. But for landlords who qualify, it's one of the most powerful mortgage acceleration strategies available in Canada. To understand the step-by-step process of implementation, see how rental cash damming works.
The best way to find out if cash damming makes sense for your situation is to speak with a specialist who understands the strategy inside and out.
This article is for educational purposes only and does not constitute tax, legal, or financial advice. The strategies described rely on specific facts and circumstances that vary by individual. Do not implement rental cash damming without first consulting a qualified tax professional and licensed mortgage professional. Freedom10 is a financial strategy and education company. Where mortgage services are required, they are provided by licensed mortgage agents and brokers at Tango Financial (ON), Brokerage License #13691. Quebec residents are referred to our licensed partner. You will be informed of all applicable licensing details before any work begins.