Treasurer Wayne Swan has described National Australia Bank's decision NOT to pass on the full quarter of a per cent cut in interest rates as a "kick in the guts to working families".

NAB has broken ranks with the other banks by only passing on point-2 of a per cent to its customers.

Mr Swan says the decision is greedy and unjustified.

But NAB group executive Lisa Gray has defended the move.

Gray says if lending rates are compared .. NAB customers still get the best deal.