T This final project report examines the implementation of an information system for tax invoice administration and vat collection at pt indo traktor utama. the study is motivated by the policy integrating the national identity number (nik) with the taxpayer identification number (npwp) mandated by the hpp law, pmk 112/2022 (in conjunction with pmk 136/2023), and per-06/pj/2024 which requires the validation of 16-digit nik/npwp numbers during tax invoice issuance. the theoretical framework encompasses concepts of accounting information systems, tax invoice administration, and vat regulations under the vat law and the general provisions and tax procedures (kup) law. this report is based on a field internship in the taxation division, utilizing data collection methods such as observing tax invoices rejected by the system, interviewing tax staff, and reviewing relevant references and regulations. the analysis reveals that the company\\\'s tax invoice issuance cycle comprises six stages; however, validation issues arising from incomplete data matching between the directorate general of taxes (djp) and the population and civil registration agency (dukcapil) frequently trigger rejections in the coretax system, potentially leading to administrative sanctions. the report concludes that implementing data collection standard operating procedures (sops) starting at the pre-transaction stage, alongside developing automated notification and pre-validation systems, can mitigate the risk of defective tax invoices in the future.