Traditional identity verification methods pose significant challenges to user privacy and security, often requiring individuals to disclose more personal information than necessary for manual verification. As the country advances toward a digital economy, the Philippine Identification System (PhilSys) provides an opportunity to shift from physical document checks to a unified and secure digital identity framework. This paper introduces MasquerAge, an age verification system leveraging the Modular Open Source Identity Platform (MOSIP). The system utilizes MOSIP-based IDs, containing QR codes aligned with PhilSys specifications, to perform secure age verification. A web application was developed to facilitate scanning QR codes and authenticating users via MOSIP APIs. Performance testing showed the system to be generally efficient; however, cryptographic processes required by MOSIP introduced noticeable latency. The results highlight the viability of a privacy-preserving age verification system while identifying areas for optimizations and security enhancements in real-world implementations.