Deciding

Does velocity banking actually work?

The surplus is the engine

Everything the strategy achieves comes from the gap between income and expenses. That surplus reduces the balance, which reduces the interest charged, which frees more of the same surplus for principal next month.

This is why the honest first question is not about the product at all. It is: what does the gap look like across your last three bank statements?

The rate comparison has to clear

You are trading a fixed rate for a variable one. If your existing mortgage carries a low fixed rate, that is a genuinely hard thing to beat, and the daily-balance benefit may not cover the difference.

Any calculator that never returns “this does not work for you” is not doing arithmetic. The comparison should be able to come out against the strategy, and sometimes it does.

Where the advantage actually comes from

Not from the interest calculation method. From retiring principal earlier.

The size of that effect is easy to underestimate. On a thirty-year loan, the same dollar applied early saves many times what it saves late, because it removes interest from every remaining month. Timing dominates.

Where it does not work

Income that cannot be documented. Surplus with no cushion behind it. An unwillingness to watch a balance every month. Any of those, and this is the wrong tool.