This study aims to analyze the transformation of tax administration in Indonesia in the digital economy era, with a focus on the implementation of the Coretax Administration System (CTAS) and the role of data analytics in promoting sustainable compliance. This research employs a qualitative approach with an interpretive case study design. In addition, participatory observation and documentation studies of relevant tax regulations and policies were conducted to enrich the data. Data analysis was performed using the Miles and Huberman interactive model through the stages of data reduction, data display, and conclusion drawing, with the application of source and method triangulation to ensure data validity. The findings indicate that Coretax implementation has brought fundamental changes to tax administration by integrating all tax business processes into a single integrated digital platform. This system enhances operational efficiency, reduces compliance costs, and strengthens transparency through automated data validation and real-time data access. The utilization of advanced data analytics, including Natural Language Processing (NLP) and machine learning, has begun to be integrated into tax audit processes and supply chain analysis to detect potential non-compliance at an early stage. However, Coretax implementation faces significant obstacles, including system complexity and technical disruptions, infrastructure and digital literacy gaps, as well as human resource and institutional adaptation challenges. This study also finds that tax administration transformation promotes sustainable compliance through compliance by design mechanisms and increased public trust, while also transforming the role of tax consultants into digital mediators and strategic advisors. This study concludes that the success of tax administration transformation is determined not only by technological sophistication but also by institutional readiness, human resource capacity, and the ability to maintain public trust through transparent, fair, and responsive governance. Keywords: Coretax Administration System (CTAS) / Coretax, Digital economy, Tax administration, Data analytics. Abstrak Penelitian ini bertujuan untuk menganalisis transformasi administrasi perpajakan di Indonesia di era ekonomi digital dengan fokus pada implementasi Coretax Administration System (CTAS) dan peran analisis data dalam mendorong kepatuhan berkelanjutan. Penelitian ini menggunakan pendekatan kualitatif dengan jenis studi kasus interpretatif. Selain itu, observasi partisipatif dan studi dokumentasi terhadap regulasi serta kebijakan perpajakan terkait juga dilakukan untuk memperkaya data. Analisis data dilakukan menggunakan model interaktif Miles dan Huberman melalui tahapan reduksi data, penyajian data, dan penarikan kesimpulan, dengan penerapan triangulasi sumber dan metode untuk menjamin keabsahan data. Hasil penelitian menunjukkan bahwa implementasi Coretax telah membawa perubahan fundamental dalam administrasi perpajakan melalui integrasi seluruh proses bisnis perpajakan ke dalam satu platform digital yang terpadu. Sistem ini meningkatkan efisiensi operasional, mengurangi biaya kepatuhan, dan memperkuat transparansi melalui validasi data otomatis serta akses data secara real-time. Pemanfaatan analisis data lanjutan, termasuk Natural Language Processing (NLP) dan machine learning, mulai diintegrasikan dalam proses pemeriksaan dan analisis rantai pasokan untuk mendeteksi potensi ketidakpatuhan secara dini. Namun demikian, implementasi Coretax menghadapi hambatan signifikan yang meliputi kompleksitas sistem dan gangguan teknis, kesenjangan infrastruktur dan literasi digital, serta tantangan adaptasi sumber daya manusia dan kelembagaan. Penelitian ini juga menemukan bahwa transformasi administrasi perpajakan mendorong kepatuhan berkelanjutan melalui mekanisme compliance by design dan peningkatan kepercayaan publik, serta mengubah peran konsultan pajak menjadi mediator digital dan penasihat strategis. Penelitian ini menyimpulkan bahwa keberhasilan transformasi administrasi perpajakan tidak hanya ditentukan oleh kecanggihan teknologi, tetapi juga oleh kesiapan kelembagaan, kapasitas sumber daya manusia, dan kemampuan menjaga kepercayaan publik melalui tata kelola yang transparan, adil, dan responsif. Kata Kunci: Coretax, ekonomi digital, administrasi perpajakan, analisis data, konsultan pajak