Estimate-based income calculation: assessee estimates now treated as total income for tax computation under amended provisions. The amendment provides that, where an assessee furnishes an estimate (including a revised estimate) under the specified pre-assessment mechanisms, that estimate shall be substituted for the assessee's total income for the purposes of tax calculation; it also inserts cross-reference language to include statements furnished under the companion pre-assessment subsection and rewords the clause to expressly encompass initial and revised estimates submitted under those mechanisms.