A DWP spokesman said: "We want to reassure pensioners claiming housing benefit that they will not be affected by this policy now, or when Universal Credit begins, even if one partner is below pension age."
He confirmed however that this would not apply to new claimants after that time.
A poll for the newspaper found that voters believed - by a majority of 46% to 35% - that the principle of the change was "only fair" at a time of economic austerity.
But clear overall majorities said that its implementation should be delayed for a rethink on how to implement it (52%), that it should only apply if people refused smaller homes (60) and that it should not apply at all to Army families with children away on active service (77%).
ComRes interviewed 2,002 British adults online from on February 13-14 2013.