Extension of assessment-year period for Section 80QQ benefits expands the available period for eligible taxpayers under the amended provision. The amendment substitutes the words in sub-section (1) of Section 80QQ to replace the shorter multi-year temporal limit with a longer multi-year temporal limit, thereby extending the statutory assessment-window during which the provision operates; the change is a textual substitution and does not alter other eligibility criteria or procedural provisions in the section.