SOC 2 PI1.3: Processing Integrity - System Inputs are Complete, Accurate, and Timely

Implement input validation at every data entry point. For web forms and user interfaces, use client-side validation for user experience and server-side validation for actual enforcement. Check data types, formats, ranges, required fields, and business rules. Never rely on client-side validation alone - it can be bypassed trivially.

For APIs, enforce strict schema validation. Define expected input formats using OpenAPI/Swagger or equivalent. Validate all incoming data against the schema before any processing begins. Add rate limiting and input size restrictions to prevent abuse. Log all validation failures with enough detail to troubleshoot.

For batch file inputs, validate headers and trailers (record counts, control totals, file identifiers), validate individual records (field formats, required data, business rules), detect duplicates, and verify completeness (did the expected file arrive with the expected number of records?). Reject entire batches when critical validation fails and produce clear error reports.

For system-to-system integrations, define data contracts specifying the expected format and content. Validate incoming data against the contract before accepting it. Implement acknowledgment mechanisms confirming successful receipt and validation. Monitor integration health and alert on failures.

Build an input error management process. Generate clear error messages that explain what went wrong without leaking sensitive system details. Give users or sending systems a way to correct and resubmit. Track error rates by source and type to catch systemic quality problems early.

Document all your validation rules for each input channel, including why each rule exists. Review and update them when processing specifications change, new data sources come online, or error analysis shows gaps in your coverage.