The Retaining Educators Takes Added Investment Now (RETAIN) Act aims to address the critical shortage of educators and school leaders in early childhood, elementary, and secondary education. It proposes a new refundable tax credit for eligible professionals, including early childhood educators, teachers, paraprofessionals, school leaders, and school-based mental health service providers. The primary purpose of this credit is to reward retention and encourage continued service, particularly in high-need educational environments. The tax credit amount is structured to increase with an individual's continuous years of employment in an eligible position. For instance, it starts at $5,800 for the first two years, increases to $7,000 for years three and four, and reaches a peak of $11,600 in the tenth year of continuous service. After the tenth year, the credit gradually decreases, becoming zero after 20 years of employment, and all dollar amounts are subject to inflation adjustment after 2026. To qualify, professionals must be employed in specific roles within "qualifying schools" or "qualifying early childhood education programs," which generally serve high-poverty areas or receive federal assistance. The bill includes a "supplementing, not supplanting" provision, prohibiting State and local educational agencies from reducing existing compensation or loan forgiveness due to an employee's eligibility for this credit. Furthermore, these agencies must demonstrate that the credit does not lead to a reduction in local funding for compensation. Beyond the tax credit, the RETAIN Act also directs the Secretary of Labor, in coordination with the Secretaries of Treasury, Education, and Health and Human Services, to establish and annually update an interagency data series. This series will capture and publish average base salaries for teachers, disaggregated by Title I status and geographic region, and for early childhood educators, disaggregated by their highest degree attained. This provision aims to provide greater transparency and insight into educator compensation trends.