All-in-one and readvanceable mortgages

How it works

A normal mortgage charges interest on the balance, and your chequing account sits somewhere else earning nothing. If you keep $18,000 floating through the month for bills, that’s $18,000 doing no work while you pay interest on your full mortgage.

An all-in-one puts them in the same place. Your pay lands and immediately reduces the balance interest is charged on. Bills come out and it goes back up. Interest is calculated daily on the net. You haven’t locked the money away. You can spend it any time, but while it sits there, it works.

On a $400,000 balance with an average $20,000 float, at 5.45%, that float saves roughly $1,090 a year. Not life-changing on its own. But combine it with a household that runs a genuine monthly surplus and never lets the balance drift back up, and the amortization shortens dramatically.

Who it genuinely suits

• The self-employed. Income arrives lumpy; HST and tax instalments sit in an account for months. Parking that against the mortgage instead of in a savings account is close to free money.
• High-surplus households who currently sweep money into savings and would rather it offset debt.
• People with irregular large expenses (tuition, property maintenance, seasonal business costs) who need genuine liquidity and hate the idea of a separate line of credit.
• Anyone consolidating who has demonstrated the discipline. This is the product I use when someone has proven, over a year, that the cards stayed closed.

Who should avoid it, honestly

I say no to this product more often than I say yes.

• If your available credit tends to become spent credit. An all-in-one has no forced amortization. Nothing makes you pay principal. Some people carry the same balance for a decade and only notice at renewal.
• If your cash float is small. No float, no saving, just a higher rate.
• If you need the psychological structure of a fixed payment. That structure is a feature, not a limitation, and there is no shame in needing it. Most people do.
• If you’re currently consolidating debt for the first time. Prove the behaviour change first, then earn the flexible product.

Compared to the alternatives

Structure comparison

	Conventional mortgage	Readvanceable (mortgage + HELOC)	All-in-one
Rate	Lowest	Mortgage portion low; HELOC at prime +	Highest, typically near prime
Forced principal repayment	Yes	Yes, on the mortgage portion	No
Access to equity	Requires refinance	Automatic as principal is repaid	Immediate
Clean tax tracing	Poor	Excellent with sub-accounts	Difficult
Best for	Most households	Investors, cash damming, Smith Manoeuvre	High-float, high-discipline households

The tax angle: where readvanceable beats all-in-one

If your interest in this product is really about tax deductibility, funding investments or a rental with borrowed money: the single-account all-in-one is the wrong tool. CRA requires you to trace borrowed funds to their income-earning use, and a single account where your groceries and your investment capital share a balance makes that tracing nearly impossible to defend.

The right structure is a readvanceable mortgage with separate sub-accounts: one for personal, one for each income-earning purpose. Every dollar traceable. That is the foundation of both the Smith Manoeuvre and rental cash damming.

Set it up wrong and the deduction can be denied years later, with interest and penalties. Set it up right at the start and it costs nothing extra. This is one of the few decisions in personal finance where the sequencing genuinely matters, which is why I’d rather have the conversation before you sign anything.

Written and reviewed by Derrick Johnston, Mortgage Agent Level 2, BRX Mortgage Inc. (FSRA #13463). Not tax advice. Confirm any interest-deductibility strategy with a licensed accountant.