Technical debt is not inherently bad. Like financial debt, it can be a useful tool when taken on deliberately and paid back systematically. The problem is unmanaged debt — the kind that accumulates silently until every change takes twice as long as it should.

The difference between high-performing engineering teams and struggling ones is often not talent, but how they manage technical debt.

Technical Debt Technical debt compounds like financial debt — small amounts become overwhelming if ignored

What Is Technical Debt

Technical debt is the implicit cost of choosing a faster or easier solution now that will require additional work later.

Types of Technical Debt

Type Description Example
Deliberate Conscious choice for speed "Ship without tests, add them next sprint"
Accidental Unknown best practices at the time Legacy patterns before modern alternatives existed
Bit rot Code degrading as requirements change Features built for old use cases
Dependency debt Outdated libraries and frameworks Running on unsupported versions
Documentation debt Missing or outdated docs Tribal knowledge not written down
Test debt Insufficient test coverage No tests for critical paths
Architecture debt System design that no longer fits Monolith that should be services (or vice versa)

All codebases have technical debt. The goal is not zero debt — it is manageable debt.

Identifying Technical Debt

Code Signals

Watch for these indicators:

High Debt Indicators:
├── Long methods/functions (100+ lines)
├── Deep nesting (callbacks, conditionals)
├── Duplicated code across modules
├── God classes/modules (does everything)
├── Magic numbers and strings
├── No tests or failing tests
├── Circular dependencies
└── Inconsistent patterns across codebase

Process Signals

Debt manifests in team behavior:

Signal What It Indicates
"Don't touch that code" Fragile, poorly understood areas
Long onboarding Complexity, poor documentation
Bugs in "unrelated" areas Tight coupling, hidden dependencies
Slow feature development Accumulated friction
Fear of refactoring No test coverage, unclear behavior
Knowledge silos Tribal knowledge, documentation debt

Measuring Debt

Quantitative metrics help track debt over time:

Cyclomatic Complexity: Higher complexity = harder to maintain

# Example: measure with ESLint
eslint --rule 'complexity: ["error", 10]' src/

Test Coverage: Lower coverage = higher risk

# Coverage report
jest --coverage

Dependency Freshness: Outdated packages = security and compatibility risk

# Check for outdated packages
npm outdated

Build Time: Increasing build times often indicate architectural problems

# Track over time
time npm run build

Prioritizing Debt

Not all debt is equal. Prioritize based on impact and risk.

The Debt Quadrant

                    High Impact
                         │
    Fix Soon             │           Fix Now
    (Important paths,    │    (Critical paths,
     moderate traffic)   │     high traffic)
                         │
────────────────────────┼────────────────────────
                         │
    Ignore/Delete        │           Fix Later
    (Unused code,        │    (Non-critical,
     legacy features)    │     low traffic)
                         │
                    Low Impact

Prioritization Criteria

Score each debt item on:

  1. Business Impact: Does this affect revenue, users, or critical features?
  2. Developer Impact: How much does this slow down development?
  3. Risk: What happens if this code fails?
  4. Fix Cost: How much effort to address?
  5. Urgency: Is there a deadline (security, deprecation)?

Example Debt Register

Item Business Impact Dev Impact Risk Cost Priority
Auth system refactor High High High Large 1
Outdated React version Medium Medium High Medium 2
Inconsistent API naming Low Medium Low Small 3
Legacy dashboard code Low Low Low Large Defer

Paying Down Debt

Strategy 1: Dedicated Debt Sprints

Allocate entire sprints to debt reduction.

Pros:

  • Focused effort, significant progress
  • Clear to stakeholders

Cons:

  • No feature progress during sprint
  • Hard to justify to business
  • Debt accumulates between sprints

When to use: Major debt reduction efforts, migration projects

Strategy 2: Percentage Allocation

Dedicate a percentage of each sprint to debt.

Sprint Allocation Example:
├── Feature work: 70%
├── Bug fixes: 15%
└── Technical debt: 15%

Pros:

  • Continuous progress on debt
  • Sustainable pace
  • Business gets features too

Cons:

  • Harder to tackle large debt items
  • May feel like death by a thousand cuts

When to use: Default approach for most teams

Strategy 3: Boy Scout Rule

Leave code better than you found it. Every PR improves something.

PR includes:
1. Feature/fix being worked on
2. One small improvement to touched code
   - Rename unclear variable
   - Add missing test
   - Remove dead code
   - Update outdated comment

Pros:

  • Zero dedicated time needed
  • Distributed responsibility
  • Gradual, continuous improvement

Cons:

  • Cannot tackle large debt items
  • Inconsistent application
  • PRs can grow in scope

When to use: Always, as a complement to other strategies

Strategy 4: Debt Tickets in Backlog

Treat debt items like features — write tickets, estimate, prioritize.

Pros:

  • Visible to stakeholders
  • Can be prioritized against features
  • Creates accountability

Cons:

  • Debt tickets often deprioritized indefinitely
  • Overhead of ticket management

When to use: For medium to large debt items that need explicit planning

Preventing New Debt

The best debt is debt never created.

Code Review Focus

Review for maintainability, not just correctness:

Code Review Checklist:
□ Is this the simplest solution that works?
□ Will someone understand this in 6 months?
□ Are edge cases handled or documented?
□ Is test coverage adequate?
□ Are dependencies justified?
□ Does this follow team patterns?

Architecture Decision Records

Document significant decisions:

# ADR-001: Use PostgreSQL for primary database

## Status
Accepted

## Context
We need a database for user data. Options: PostgreSQL, MySQL, MongoDB.

## Decision
PostgreSQL because: JSONB support, strong ecosystem, team familiarity.

## Consequences
- Need PostgreSQL expertise for operations
- Migration from MongoDB required for legacy data
- Cannot use MongoDB-specific features

ADRs explain why decisions were made, preventing future "why did we do this?" debt.

Definition of Done

Expand your definition of done:

Feature is "done" when:
□ Code is written and working
□ Tests are passing
□ Code is reviewed
□ Documentation is updated
□ No new linting errors
□ Performance is acceptable
□ Accessibility is checked
□ No obvious tech debt introduced

Refactoring Windows

Build refactoring into feature work:

Feature Development Pattern:
1. Understand existing code
2. Refactor to make change easy (small PR)
3. Make the easy change (feature PR)
4. Clean up any mess created (small PR)

This "preparatory refactoring" reduces friction and prevents debt accumulation.

Communicating About Debt

To Engineering Leadership

Frame debt in terms of velocity and risk:

  • "Our deployment time has increased 3x in 6 months. Addressing build pipeline debt would save X hours per week."
  • "This legacy system has no test coverage. A bug here could cause Y business impact with Z probability."

To Product/Business Stakeholders

Translate to business terms:

Technical Term Business Translation
Refactoring Restructuring for faster future development
Test coverage Insurance against bugs in production
Dependency updates Security and compatibility maintenance
Architecture debt System design limiting our growth options

In Sprint Planning

Be specific about tradeoffs:

  • "We can ship this in 2 days with debt, or 4 days done properly. The debt will cost us 3 days to fix later."
  • "This feature touches the payment code. We should add tests first (2 days) to ship safely."

The Debt-Free Myth

Some debt is acceptable and even optimal:

Good debt:

  • Conscious tradeoff for market timing
  • Throwaway prototypes
  • Code that will be replaced soon
  • Low-traffic, low-risk areas

Bad debt:

  • Debt in critical paths
  • Debt without awareness
  • Debt without payback plan
  • Debt that compounds (affects every future change)

The goal is not zero debt. The goal is intentional debt with a plan for repayment.

Practical Steps

  1. Assess current state: Create a debt inventory with impact and cost estimates
  2. Choose a strategy: Percentage allocation works for most teams
  3. Make debt visible: Track in your project management tool
  4. Prevent new debt: Code review, ADRs, definition of done
  5. Review regularly: Monthly debt review to reprioritize
  6. Celebrate progress: Acknowledge debt reduction wins

Technical debt is a fact of software development. Managing it intentionally is what separates codebases that improve over time from those that slowly become unmaintainable.

Comments