This study aims to determine the notes, documents, depreciation method, and fixed asset control system used by PDAM Tirta. This type of research is quantitative and
qualitative with primary and secondary data sources. Data collection was carried out through observation, interviews, and document documentation (DPB, OP, BPP, Receipt, DPI, SPK BPP, MPAT, JU, BPAT Vouchers and Flow Charts). The results of this study indicate that the fixed assets of PDAM Tirta Merapi are obtained by buying cash, using documents such as a list of requests for goods, purchase orders, receipt of goods, receipts, inventory signs, work orders, proof of requests and expenses, and a termination memo. Two methods of depreciation are used, namely Straight-Line Depreciation and Multiple Depreciation Balance. The internal control system for fixed assets of PDAM Tirta Merapi has been running well, as evidenced by the reports carried out by the leadership. The acquisition of fixed assets must also be approved by the division so that an application for the acquisition of
fixed assets is submitted to the President Director.