The Finance Act 2020 introduced significant amendments to the VAT & SD Act of 2012, including a revised definition of 'input' that excludes labor and specific items while incorporating machinery. Key changes also include the elimination of the registration threshold for VAT and the extension of the input tax credit timeline, enhancing taxpayer benefits. Additionally, the act updates tax rates, procedures for VAT deductions at source, and refund policies to streamline operations and clarify tax obligations.