Recovery of Several Sums in one complaint etc

All or any of the sums due in respect of tax from any person and payable to the Commissioner (being sums which are by law sums enforceable as a civil debt) may, whether or not they are due under one assessment, be included in the same complaint, summons, order, warrant, or other document required by law to be laid before a Magistrate or to be issued by a Magistrate, and every document as aforesaid shall as respects 76 such sum be construed as a separate document and its invalidity as respects any one such sum shall not affect its validity as respects any other such sum.