All taxpayers in Indonesia, starting January 1, 2025 must carry out their tax obligations using the Coretax Administration System (CTAS). The new tax system implemented in Indonesia aims to integrate all tax obligations, both the PPh 21 application, the unification application (PPh 15,22, 23/26 and 4 paragraph 2) and the VAT application into 1 (one) application called the Coretax System. In accordance with Presidential Regulation (Perpres) No. 40 of 2018 concerning the Renewal of the Tax Administration System, this digital transformation is expected to be able to load the business process of implementing tax administration, both from the DJP side in implementing and for taxpayers in fulfilling their tax obligations. Community Service (PKM) is carried out for UMKM PT RS to carry out tax obligations according to PMK No. 81 of 2024, namely the implementation of tax rights and obligations digitally, taxpayer registration procedures, confirmation of Taxable Entrepreneur (PKP) status, tax payment and deposit mechanisms, and the process of organizing and managing Tax Notification Letters (SPT). Partner issues: limited Company staf capabilities because the system implemented is integrated between other taxes and concerns about errors in implementing the Coretax system which can result in interest sanctions, administrative sanctions and even the possibility of a tax audit by the Directorate General of Taxes. The method used through assistance in the implementation of the Tax Administration System (CTAS) to Increase the Efficiency of Calculation, Deposit and Tax Reporting by coming directly to the partner's location. The output produced is that the Company can fulfill its tax obligations correctly in accordance with applicable regulations. The results of the implementation of the activity were presented at a seminar in Serina held by Tarumanaga University and an HKI poster. ABSTRAK Semua wajib pajak di Indonesia, mulai 1 Januari 2025 harus melaksanakan kewajiban perpajakan menggunakan Coretax Administration System (CTAS). Sistem perpajakan baru yang diterapkan di Indonesia, bertujuan untuk mengintegrasikan semua kewajiban perpajakan baik aplikasi PPh 21, aplikasi unifikasi (PPh 15,22, 23/26 dan 4 ayat 2) dan aplikasi PPN ke dalam 1 (satu) aplikasi yang dinamakan Coretax System. Sesuai Peraturan Presiden (Perpres) No. 40 Tahun 2018 tentang Pembaruan Sistem Administrasi Perpajakan. Transformasi digital ini diharapkan dapat menyederhanakan proses bisnis pelaksanaan administrasi perpajakan, baik dari sisi DJP dalam melaksanakan tugasnya maupun bagi wajib pajak dalam memenuhi kewajiban perpajakannya. Pengabdian Kepada Masyarakat (PKM) dilaksanakan kepada UMKM PT RS untuk melaksanakan kewajiban perpajakan sesuai PMK No 81 Tahun 2024 yaitu pelaksanaan hak dan kewajiban perpajakan secara digital, prosedur pendaftaran wajib pajak, pengukuhan status Pengusaha Kena Pajak (PKP), mekanisme pembayaran dan penyetoran pajak, serta proses penyampaian dan pengelolaan Surat Pemberitahua (SPT) pajak. Permasalahan mitra: keterbatasan kemampuan staf perusahaan karena sistem yang diterapkan terintegrasi antar pajak lainnya dan kekuatiran terjadinya kesalahan melakukan implementasi Coretax System yang dapat menimbulkan sanksi bunga, sanksi administrasi bahkan kemungkinan dilakukan pemeriksaan pajak oleh DJP. Metode yang dipakai melalui pendampingan implementasi Tax Administration System (CTAS) Untuk meningkatan efisiensi penghitungan, penyetoran dan pelaporan pajak dengan datang langsung ke lokasi mitra. Luaran yang dihasilkan yaitu Perusahaan dapat memenuhi kewajiban perpajakan dengan benar sesuai dengan peraturan yang berlaku. Hasil dari pelaksanaan kegiatan diseminarkan di Serina yang diadakan oleh Universitas Tarumanagara dan poster HKI.