Worked on the hmrc/pillar2-submission-api repository to deliver a comprehensive documentation upgrade for the Pillar 2 Submission API. Focused on technical writing and documentation using Markdown, the work introduced detailed guides covering error handling, fraud prevention, testing, and versioning, while also updating the API overview to align with new Pillar 2 regulations. This approach aimed to streamline developer onboarding and clarify integration requirements, ensuring that API behavior and constraints are transparent. No bug fixes were addressed during this period, as the primary objective was to enhance knowledge transfer and support engineering efforts through improved, well-structured documentation resources.