the date which may be specified for the purposes of subsection (2) or subsection (4) shall be not later than F231st July following the end of the tax year to which the notice relates, or 30 days after the date on which the notice is given, if later; and

the date which may be specified for the purposes of subsection (8) shall be not later than 31st January following the end of the tax year to which the notice relates, or 30 days after the date on which the notice is given, if later.