Apartment Maintenance App - Development

I'm looking to create an Android app focused on managing flat/apartment maintenance charges. This productivity tool should facilitate the payment and collection of these charges.

Core functionality includes:
- Online payment processing
- Automated reminders
- Expense tracking

Ideal skills and experience:
- Proven Android app development expertise
- Experience integrating online payment systems
- Familiarity with setting up automated reminders
- Ability to develop expense tracking features

Please provide a portfolio showcasing similar projects.