How to model velocity banking with it, using the “Apply at month(s)” field:
| What you want to model | What to type |
|---|---|
| One $15,000 chunk, four years in | 49 with the chunk as your extra payment |
| A chunk every eight months, ongoing | 1/8 |
| Six chunks then stop | 1/8 x6 |
| Save the surplus first, then chunk | save 2000 |
| Start chunking in year five | 61-payoff |
That last group is the one most velocity banking spreadsheets cannot do, and it matters, because almost nobody starts on day one.
Now the part most of these pages skip
If you are here, you have watched a video where someone paid off a mortgage in seven years and the arithmetic looked airtight.
It mostly is. That is what makes it convincing. And it is also why the honest answer is more useful to you than another enthusiastic spreadsheet.
Here is what is actually going on.
Where the savings really come from
Velocity banking works. It just does not work for the reason the videos say.
The strategy has two parts and they are wildly unequal.
Part one: the chunk. You draw a lump sum from your line of credit and throw it at your mortgage principal. This is where essentially all of the benefit lives. Front-loading principal genuinely does save enormous interest, because interest is charged on what you still owe.
Part two: the float. You run your income through the line so idle cash sits against the balance and reduces your average daily interest. This is real, and it is small. The commonly cited figure: an $8,000 paycheck parked at 8% for fifteen days before expenses draw it out saves about $33.
The critics’ central point is correct, and we are not going to pretend otherwise: you could make the same chunk payments without a line of credit at all. If you have the surplus to repay a chunk over eight months, you have the surplus to pay that money against your mortgage directly — and you would save slightly more, because you would not be paying line-of-credit interest on the way.
So anyone telling you the line of credit is where the magic lives is selling you something.
What is actually true about it
If it were simply worse, nobody would do it. Four things are genuinely true.
It front-loads. Chunking gets a large sum against principal now rather than dripping it in over years. Earlier money does more work, and the difference is not small.
It enforces discipline. A drawn balance on a line of credit demands to be repaid in a way that a vague intention to pay extra does not. For a lot of households, that is the entire value — and it is a real one, even if it does not appear in anybody’s arithmetic.
The float is real. Small, but not nothing, and it compounds over years.
And the money stays reachable. This is the one nobody weighs properly. A dollar paid against your mortgage is gone — to get it back you must borrow. A dollar sitting against a line of credit reduces your interest and can be drawn again tomorrow if the furnace dies. That is not a rounding difference. For most households it is the difference between a plan that survives a bad year and one that does not.
What it actually costs
A second debt against your home. The line is secured. Falling behind on it has the same consequences as falling behind on a mortgage.
A variable rate. Nearly all lines are. Your chunk repayment cost moves with Prime and you do not control it.
A draw period that ends. Typically ten years in, the line stops revolving and converts to repayment over a shorter term. Payments can rise sharply. People are blindsided a decade after they stopped thinking about it, and mid-strategy is the worst possible moment.
And it amplifies whatever habits you already have. Discipline plus a line of credit is a powerful combination. Poor habits plus a line of credit is a much larger hole, arrived at faster. This is not a small print risk — it is the most common way this ends badly, and we have watched it happen.
What a free calculator cannot tell you
Every velocity banking calculator, ours included, has to assume things away.
They assume your line’s rate never moves. It will.
They assume your income and expenses are flat for a decade. They will not be.
They assume you never miss a cycle. Someone will get married, or ill, or made redundant.
They assume the draw period never ends, which is the single most consequential omission of the lot.
And most assume you start today — which almost nobody does, and the cost of waiting is larger than people expect.
Use the calculator. It will tell you the shape of the thing. Just do not mistake a clean line on a chart for what the next ten years will actually look like.
What we do differently, and honestly
We have been doing this since 2006. Bill Westrom and I brought Macquarie Mortgages’ Asset Manager to American homeowners — the first true first-lien line in this market — and when Macquarie left after the crash we built something else out of what we had learned.
So here is our honest position, and it is not that the arithmetic is magic.
We use a small line in second position. Your first mortgage stays exactly where it is. Across 946 real customer files modelled both ways, the first-lien route puts a median of $223,000 onto a variable rate. Ours puts $33,000. TIE engine analysis, 2026-08-23.
We do not claim to be faster. On the same files, the first-lien structure actually finishes sooner more often than ours does. We are not going to hide that. What ours does is get there with a fraction of your money exposed to a rate you do not control.
And we tell people when it will not work. If you spend more than you earn, none of this helps — it accelerates whichever direction your cash flow already points. We say that on the call rather than take the money.
On a household five years into a $340,000 mortgage at 3.5% — balance $304,970, ordinary cash flow, no additional money to spare:
| Paid off in | 10 years 2 months |
| Interest from today | $57,607 |
| Extra money required each month | none |
| Cash reachable if something breaks | $5,000 |
| Refinance required | none |
Against the original schedule: 25 more years and $153,056 of interest still to pay.
TIE amortization tool and PB engine, 2026-08-22.
If you are weighing the line itself rather than the strategy, we have written an honest account of HELOC pros and cons, and of what credit line banking actually involves.
Run it on your own numbers
No signup, no email. Model the chunks yourself.
A few minutes, no card. Your balance, your rate, your income, your expenses.
And if the honest answer is that this is wrong for you, it will say so. We would rather tell you on a call than four years in.
Frequently asked
Is velocity banking a scam?
No. It is a real strategy that genuinely accelerates a mortgage. What is oversold is the reason it works — the benefit comes overwhelmingly from front-loading principal, not from routing your paycheck through a line of credit.
Can I do it without a HELOC?
Yes, and mathematically you would do slightly better. What you would lose is the enforced discipline and the ability to reach the money again — and for many households those are worth more than the small arithmetic difference.
How big should a chunk be?
Small enough that your surplus can repay it in roughly three to six months. Sizing it too large is the most common mistake — the balance sits there accruing interest and eats the benefit.
What if my rate is 3%?
Then be careful. A low fixed mortgage is the cheapest money most households will ever hold, and moving any of it to a variable line at double the rate needs a reason beyond enthusiasm. This is exactly the case where the second-lien approach matters — a small line beside your mortgage rather than instead of it.
Does it work with a credit card instead?
People do it. The rate is far higher and the limit far lower, and the discipline required is greater. We would not.
What happens when the draw period ends?
Your line stops revolving and converts to repayment, often over a much shorter term, and payments can rise a lot. Ask your lender for the exact terms before you start, not five years in.