Worked on the mautic/mautic repository to deliver unified UTC date and time handling across the application, addressing inconsistencies caused by varying time zones. Updated core backend logic in PHP to ensure all datetime and date-only fields are processed and stored in UTC, including modifications to the CustomFieldHelper component. Incorporated robust unit testing to validate UTC conversions and addressed daylight saving time by using fixed offsets, resulting in DST-stable test coverage. This approach improved cross-region data consistency, enhanced scheduling reliability, and strengthened the overall test suite. The work focused on maintainable, targeted changes using PHP and backend development best practices.