4.2The Cost of Late Bug Detection

The cost of fixing a bug increases exponentially the later it is found:

Stage Found	Relative Cost	Why
Requirements	1x	Change a document
Design	5x	Redesign before building
Development	10x	Rewrite code
Testing	20x	Find, report, fix, retest
Production	100x	Incident response, customer impact, reputation damage

A missing validation rule caught during requirements review costs 15 minutes to fix. The same missing validation discovered in production through a security breach costs thousands of dollars and months of remediation.