A data retention policy defines how long an organization keeps different categories of data and what happens when the retention period expires. Within the Empty Fortress doctrine, retention policy is the temporal dimension of data minimization — it is not enough to minimize what you collect, you must also minimize how long you keep it.
Organizations face competing pressures. Legal hold requirements demand preservation. Compliance frameworks specify minimum retention periods. Business units want to keep everything forever for analytics. Meanwhile, every day data persists is another day it can be breached. The retention policy must balance these tensions with clear rules.
Start with a data inventory categorized by type: financial records, customer PII, employee data, operational logs, communications, intellectual property. For each category, determine the legal minimum retention period based on applicable regulations (SOX, HIPAA, GDPR, industry-specific rules). Set the maximum retention period as close to the legal minimum as the business can tolerate. Define the destruction method: cryptographic erasure, secure deletion, physical destruction for media. Assign ownership: who is responsible for enforcing retention and destruction for each data category.
Retention policies that depend on manual compliance fail. Implement automated lifecycle management: database TTLs, cloud storage lifecycle rules, email archival and purge schedules, automated legal hold flags that override normal deletion. Audit retention compliance quarterly.
The Empty Fortress standard for retention is aggressive: if you cannot articulate a specific, current business or legal reason to keep a piece of data, delete it now. Default retention should be the shortest defensible period, not the longest. Data at rest is data at risk.
Retention policy is temporal data minimization. Set maximum retention as close to legal minimum as possible. Automate enforcement — manual retention compliance always fails. Default to deletion, not preservation.