Advance tax intimation: Form 28A filing required when assessing officer's income estimate exceeds taxpayer's, signed by authorised signatory. If the Assessing Officer's estimate of income exceeds the assessee's estimate, the assessee must file Form 28A intimating estimated income and advance tax, signed by a person authorized to sign the return. Registered firms must submit the firm's estimate; individual partners must submit their own estimates including their share of firm income. Where an HUF's total income is likely to exceed the not-taxable limit, a declaration is required from all members.