Core Viewpoint - The article discusses the timing of tax obligations for various transactions, emphasizing the importance of understanding when tax liabilities arise based on different scenarios. Group 1: Tax Obligation Timing - The tax obligation for sales is determined by the date of receipt of payment or the date of obtaining the sales payment request, with examples illustrating different scenarios [4][5]. - For deemed taxable transactions, the tax obligation occurs on the day the transaction is completed, such as donations made by companies [7]. - In the case of imported goods, the tax obligation arises on the day of customs declaration [9]. Group 2: Special Provisions - For large machinery, ships, and aircraft with production periods exceeding 12 months, the tax obligation occurs on the day of receipt of payment or the contractually agreed payment date [13]. - When services are sold with upfront payment followed by installment or phased delivery, the tax obligation is determined by the earlier of the actual service start date or the contractually agreed date [13]. - For real estate sales, the completion of ownership registration or actual delivery determines the timing of the tax obligation [13].