You are in the final stages of acquiring a B2B SaaS platform. The commercial diligence checks out. The Quality of Earnings (QoE) report looks clean. Your technical due diligence provider runs a standard code scan, flags a few "critical vulnerabilities," and estimates remediation costs at $500,000 post-close. You bake that into the 100-day plan and sign the deal.
Six months later, the product roadmap is frozen. The VP of Engineering is asking for three more headcounts just to "keep the lights on." A simple feature integration that was supposed to take two weeks has dragged on for two months. You aren't just paying $500,000; you are paying a recurring tax on every single hour of engineering time.
This is the Technical Debt Trap. Most Operating Partners treat technical debt like a one-time CapEx repair bill—like fixing a leaky roof. But in software, technical debt is not a repair cost; it is a variable interest rate that compounds daily. When you rely on automated code scans (like SonarQube) during diligence, you are only seeing the "syntax errors"—the tip of the iceberg. You are missing the architectural coupling, the spaghetti dependencies, and the manual release processes that actually kill velocity.
If your diligence report says the debt is $X, the real cost to your EBITDA is likely 3X. Here is why the math is broken, and how to fix it before you write the check.
The discrepancy between estimated and actual technical debt comes from a fundamental misunderstanding of what debt actually is. It is not just "bad code." It is the structural rigidity that prevents value creation.
Standard diligence estimates the cost to fix the code. It ignores the cost to live with the code while you fix it. According to McKinsey, technical debt amounts to 20-40% of the entire value of the technology estate. More critically, 10-20% of the budget intended for new products is permanently diverted to resolving debt issues.
If you have a $10M engineering budget, $2M to $4M is vanishing into the ether annually. That is not a one-time fix; that is a permanent drag on your P&L that reduces your effective R&D spend.
It gets worse at the contributor level. Stripe's research indicates that developers spend approximately 33% of their time (about 13.5 hours per week) dealing with technical debt and bad code. If you are paying for 50 engineers, you are effectively only getting the output of 33. The other 17 are being paid full salaries to wrestle with legacy complexity.
This "ghost headcount" is rarely factored into the deal model. You calculate synergy based on headcount reduction, but you can't reduce headcount when 33% of your capacity is locked up in maintenance. This is often why inefficient DevOps practices remain hidden until post-close.
The most expensive part of technical debt isn't the engineering salary; it's the delayed revenue. If "spaghetti code" delays your AI integration by two quarters, you haven't just lost the cost of the engineers; you've lost the first-mover advantage and potentially churned customers to a faster competitor. Gartner predicts that by 2025, technical debt will consume more than 40% of current IT budgets, effectively capping innovation for firms that don't aggressively remediate.
Stop accepting qualitative assessments like "the code is messy." Demand quantitative answers that map to the P&L. If you are looking to stop buying broken code, you need a new diligence playbook.
Automated tools find syntax errors. They do not find architectural deadlock. Ask your technical diligence provider to map the Cyclomatic Complexity and Dependency Coupling of the core modules. If Module A cannot be changed without breaking Module B, C, and D, your remediation estimate needs to triple because you cannot refactor in isolation. You have to rebuild.
Ask for a breakdown of engineering tickets from the last 12 months. Categorize them into "New Features" vs. "Bug Fixes/Maintenance." If the ratio of Maintenance is above 30%, you are buying a distressed asset, regardless of what the revenue growth says. Use this ratio to adjust the working capital peg or demand a specific specific indemnity for the remediation period.
Do not treat remediation as an "add-back." Treat it as a necessary operational expense to unlock the exit multiple. If you need to spend $2M to decouple the monolith, that $2M is the price of admission to sell the company at a 6x revenue multiple instead of 3x. Frame the investment as Margin Expansion CapEx.
The goal isn't zero debt. The goal is managed debt. As a PE sponsor, your job is to ensure you aren't paying a premium for a "turnkey" platform that is actually a "fixer-upper." Adjust your estimate. Triple the timeline. And if the numbers still work, then—and only then—do you sign.
