(11)If, in a case where payment by instalments is allowed under sub-section (5), the assessee commits defaults in paying any one of the instalments within the time fixed under that sub-section,––(a)the assessee shall be deemed to be in default as to the whole of the amount then outstanding; and(b)the other instalment or instalments shall be deemed to have been due on the same date as the instalment actually in default.
