Every startup accumulates technical debt. The question is not whether you have it, but whether you manage it or let it manage you.
In the early days, speed is everything. Shipping an imperfect feature to validate demand is the right call. But I have seen a consistent pattern in startups that raise Series A and then stall: they cannot ship new features because every change breaks something else. Their codebase has become a minefield.
The inflection point typically comes between 10 and 25 engineers. Below 10, everyone knows the codebase and can work around the debt. Above 25, new engineers spend more time fighting the system than building features. Between 10 and 25 is when you must invest in paying down debt — and when founders resist most because they feel the pressure to ship.
My advice: dedicate 20% of engineering capacity to debt reduction at all times. Not 20% of sprints — 20% of every sprint. This prevents the accumulation from reaching critical mass and normalizes quality work as part of the culture, not a special project.
If you are already past the inflection point, the only honest solution is a partial rewrite of the most critical paths. It will feel slow. It is faster than the alternative: watching your best engineers quit because they hate working in your codebase.