Reopening of tax assessments allows reassessment at respective-year rates; proceedings may be dropped if assessed amount covers escaped income. Assessment, reassessment or recomputation on reopening is chargeable at the rates that would have applied had the income not escaped; the Assessing Officer may drop reopening proceedings if the taxpayer shows the original assessment or computation was not lower than the liability including the escaped income, provided the taxpayer did not contest the original order. Transitional provisions preserve the prior reopening regime for cases connected to searches, requisitions, surveys or notices initiated before a specified legislative cutoff.