Mandatory return filing expanded to additional exempt entities; revised return window extended to end of assessment year. The amendment expands mandatory return-filing to include specified exempt persons, Investor Protection Fund variants, Core Settlement Guarantee Fund, and Boards or Authorities among exempt entities. It also amends the revised-return timeline so a taxpayer may file a revised return up to the end of the relevant assessment year or before completion of assessment, whichever is earlier. These changes apply prospectively from the stated effective date to the indicated assessment year and subsequent years.