S. 147 : Reassessment-After the expiry of four years-No failure to disclose material facts-Reassessment not valid-Accumulation of income-Claim that 15 Per Cent. of gross receipts should be allowed to be carried forward and up to 85 Per Cent. of gross receipts required to be applied in a year-Corpus donation-Excess application of preceding assessment year can be set off against current year’s receipts. [S. 11, 148]