HACKER Q&A
📣 mikewarot

What's the interest rate on technical debt?


It seems we're now stuck with the term "Technical Debt" to describe things needing cleanup. Non-technical people need a number we can use to express just how expensive putting off cleanup will be to make rational decisions we can all live with.

What is your personal estimate of the interest rate we pay on technical debt?

My personal opinion is that it's around 100% per month, that is every hour of refactoring put off for a month doubles in size. That is, it wastes an hour elsewhere, AND still needs to be done.

Or is the interest, just how much more code we have to write to work around the debt?

Also, what units is the denominator in the fraction? Is it code size, functionality, or just calendar time?

  👤 duped Accepted Answer ✓
Debt is the wrong word, it's more like asset depreciation. The software had a cost to create, and it created some value immediately. Over the lifetime of the software the maintenance costs will eventually overtake the value that it originally provided.

So the question is not how much interest is there on tech debt, but rather what point does the cumulative maintenance of the system overtake the value it created. That's the point that it needs to be replaced.

But good luck, replacing a truck that barely works but gets you to the job site is just as tricky as replacing software that doesn't serve any good.

👤 gregjor
On average, zero. Lots of software gets replaced or tossed before the debt comes due. Having to listen to that one person on the team stress about tech debt takes a toll, though.
👤 alexfromapex
Don’t worry about interest worry about not making any payments, usually if you can pay off a little debt every cycle you’ll be fine