Burden to prove unaccounted income: additions require admissible evidence, not assumptions from survey reports.
Burden to prove alleged unaccounted income lies with the revenue; additions based on survey findings and an Inspector's report to re fix sale prices must be supported by admissible evidence. The taxpayer used the percentage of completion method for construction income, and impounded documents from a statutory survey were central to the dispute. Additions founded mainly on assumptions or inspector notes, without corroborative proof linking seized material to unexplained receipts, are susceptible to appellate review.