"We need good, strong families to help our society work well. We will support families to stay together." - Conservative Manifesto 2010, page 6.
Some couples will have to find an additional 8 hours work per week to qualify for working tax credit, as the threshold has risen from 16 to 24 hours, while that for lone parents remains at 16 hours.
Those unable to find extra work will see their income drop by £3,870 - plunging over 212,000 couples with 470,000 children into poverty.
The UK Government ignored calls from child poverty campaigners to delay the change until Universal Benefits came into force in 2013.
This attack on low earning couples comes as family budgets are already under immense pressure from soaring food and fuel prices, high childcare costs and caps to other benefits.
The SNP Work and Pensions spokesperson, Dr Eilidh Whiteford MP, said
"When David Cameron was campaigning he claimed he would do everything he could to strengthen and support families.
“Yet at the flick of a pen the Tory-Lib Dem coalition have condemned thousands of families into poverty with this savage cut.
“The loss of working tax credit could make people financially better off as single parents. The changes could not only break up families, but prevent lone parents from getting together.
“These ill-thought out reforms are the latest of a series of attacks on the pockets of the poorest in society.
“From a pasty tax to soaring fuel costs, the Conservatives and their Lib-Dem sidekicks are making life tougher for lower earners while giving tax breaks to millionaires.
“Scottish Labour may carp from the sidelines but they still prefer to see Scottish families ground down by Tory-Lib Dem rule than create a fairer society in Scotland.”