Iain Duncan Smith will use the example that, according to latest figures, 300,000 children have been moved out of relative poverty on the current measure.
But that was due to the median income nationally falling rather than to any improvement in circumstances for those children.
He will say: "For the 300,000 children no longer in poverty according to the official statistics, life was no different".
More top news
Weather set to stay cool and cloudy tomorrow
Europe's asylum, immigration and freedom of movement laws "wholly inadequate" to deal with arrival of hundreds of thousands of people.
A passenger who helped foil a suspected terror attack on a high-speed train in France is to appear on US show "Dancing With The Stars".