Developed a monthly invoice retrieval feature with input validation for the ctc-uci/lpa repository, focusing on supporting accurate financial reporting and analytics. Leveraging Express.js, Node.js, and SQL, the work introduced month-based filtering by querying invoices between the first and last days of a specified month, while also validating date formats to reduce erroneous queries. The implementation modified backend routes to ensure only valid, relevant data is returned, directly addressing requirements in PR #51. This feature improved the reliability of monthly reporting, reduced invalid queries, and established a technical foundation for future enhancements in revenue recognition and financial analytics workflows.