Power to assess in case of escape from assessment.

If for any reason any employer or other person liable to pay the tax on employment has escaped assessment in any half-year, the assessing authority may, at any time within three years from the date on which such person should have been assessed, serve on such person a notice assessing him to such tax and demanding payment thereof within such time as may be specified in the notice, and the provisions of this Act shall, so far as may be, apply as if the assessment was made in the half-year to which such tax relates.