Technical debt is like a new credit card, it often comes with a 0% introductory interest rate. In the short term tech debt can look like a win; you get the new feature on time, you automate a manual process, you patch the bug. Maybe the implementation wasn’t perfect, but dealing with a bit of funky code or living with a few bugs is better than missing the deadline.
That loan comes due right away, you have to live with what you wrote, but the interest comes later. In a month (or three or six) something will happen that magnifies the impact of that funkiness or those bugs. You’ll need an unrelated feature but because you monkey-patched in the config for the first feature you’ll be forced to rewrite the config system before you can start, adding days to your timeline. You’ll need to install a zero-day security patch but your runtime hack will force you to shut down before you can patch, causing an outage.
Like a credit card, tech debt is manageable. If you pay back the new card on the right schedule it can get you the new TV without making you miss a rent payment. If you clean up your runtime hack in the next couple weeks it’s unlikely that a zero-day patch will be released before you’re done. If you don’t pay it back or you take out too many new cards, you can end up like the guy who makes six figures but rents a basement because his credit cards cost him $3,000 every month. You’ll fall behind on new feature development because you can’t build anything without fixing three old hacks first.
Unlike a credit card, the introductory rates of tech debt are hard to predict. You don’t know how many months of freedom from interest you get, and they may expire at the worst times. That zero-day patch might come out the week after you push your funky code to prod and you’ll be stuck with an outage. You might gamble if you know you’ll still be within the month’s SLA, but if you’ve gambled on twenty things like that you’ve got great odds that the bill on several debts will blow up at a bad time.
Every win has to come with hard questions about the debt it sits on. How much of this implementation will we be forced to rewrite? Does this new feature really work or does it just mostly work but we haven’t looked deep enough to see the problems? Do the funky parts of this code overlap with upcoming work?
Loans can get you ahead, and are manageable if you’re careful, but if you win by taking out too many it won’t matter how far ahead they got you. You’ll fall behind when they get too heavy. You’ll be a six figure team living in a basement.