OFWs can contribute to the Social Security System (SSS) as self-employed individuals by enrolling through the SSS website or their nearest SSS branch. The contribution rate is based on the declared monthly earnings, and it's essential to choose a salary bracket that reflects your income. Contributing as a self-employed OFW allows you to avail benefits like retirement, sickness, and maternity. For detailed information on contribution rates and benefits, it's best to refer to the official SSS website or contact their customer service for guidance tailored to your specific situation.