Home Postcode finder WA Mount Jackson Mount Jackson postcode WA Mount Jackson is a locality in Western Australia covered by postcode 6426. Postcode 6426 State or territory Western Australia (WA) Region Wa Subs 1 G Flds Add a free Mount Jackson business listing Be the first listing in Mount Jackson Common questionsWhat is the postcode for Mount Jackson?Mount Jackson, WA has the postcode 6426.What state is Mount Jackson in?Mount Jackson is in Western Australia (WA).Does postcode 6426 cover more than one suburb?Yes. Postcode 6426 covers 14 localities, so the postcode alone does not identify Mount Jackson. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.