Purchase registers require categorisation of purchases by input tax credit eligibility and detailed invoice and seller identification. Form DVAT-30 requires dealers to record invoice-level purchase details-seller name and TIN, invoice/delivery note numbers, dates, tax rates-and to categorise purchases into those eligible and not eligible for input tax credit by source (local, inter-state, import), type (capital goods, goods, works contract) and special categories; totals and input tax paid for eligible purchases must be entered, with debit/credit note numbers indicated with +/- as applicable.