This study aims to evaluate the effectiveness and internal control of using the Accurate 5 Accounting Information System at UD XYZ, a distribution and marketing company under PT ABC. A descriptive qualitative approach with a case study method was employed to explore system implementation through in-depth interviews, document analysis, and literature review. The findings indicate that Accurate 5 has improved the efficiency of transaction recording, financial reporting, and inventory management through automated journal entries, integrated modules, and real-time report access. However, internal controls remain suboptimal due to limited implementation of transaction authorization, audit trail monitoring, and data backup processes. Other challenges include insufficient staff training and inconsistent data entry discipline. This study highlights that the successful implementation of an AIS is determined not only by technology but also by internal policies, human resource competencies, and procedural consistency. Penelitian ini bertujuan untuk mengevaluasi efektivitas dan pengendalian internal penggunaan Sistem Informasi Akuntansi Accurate 5 pada UD XYZ, sebuah perusahaan distribusi dan pemasaran di bawah PT ABC. Pendekatan kualitatif deskriptif dengan studi kasus digunakan untuk menggali implementasi sistem, melalui wawancara mendalam, studi dokumentasi, dan analisis literatur. Hasil penelitian menunjukkan bahwa Accurate 5 telah meningkatkan efisiensi pencatatan transaksi, pelaporan keuangan, dan pengelolaan persediaan melalui fitur jurnal otomatis, integrasi modul, serta akses laporan real-time. Namun, pengendalian internal belum optimal karena keterbatasan penerapan otorisasi transaksi, monitoring audit trail, dan proses backup data. Tantangan lain mencakup kurangnya pelatihan staf dan kedisiplinan input data. Penelitian ini menegaskan bahwa keberhasilan penerapan SIA tidak hanya ditentukan oleh teknologi, tetapi juga oleh kebijakan internal, kompetensi SDM, dan konsistensi prosedur.