Excise return filing requirement broadened by replacing 'filed monthly returns' with 'filed returns', simplifying eligibility. The amendment substitutes the words 'filed monthly returns' with 'filed returns' in clause (a) of the first proviso to sub section (1) of section 32E of the Central Excise Act, thereby removing the explicit monthly filing frequency from that proviso and broadening the descriptive filing requirement without altering other text of the section.