Incitec Pivot has flagged a $236 million impairment hit in its first-half results but says some of the costs will be offset by a one-off cash benefit from the US taxation reforms.

The company expects a non-cash goodwill impairment charge in regards to its industrial explosives and blasting services business, Dyno Nobel Asia Pacific, but says it remains positive for the medium to long term growth outlook for the division.

Incitec also expects a one-off benefit of $96.5 million as a result of the US government enacting tax reforming legislation which reduces the federal tax rate from 35 per cent to 21 per cent from 2018.