When the assessor shall have completed his work of assessing, valuing, and equalizing property which has been listed for taxation in his county, and such valuation shall have been entered on the assessments lists, which shall not be later than the last Monday in February of each year, he shall certify over his signature to the correctness of his returns, showing valuations fixed by him, and he shall at once notify the Department of Revenue by certified or registered mail that he has completed his assessment, valuation, and equalization work and that the tax returns are ready for the review and inspection as provided for in this title. Such lists of property shall be by the assessor delivered to the board of equalization not later than the second Monday in March.