Clash over £700m tax credits claim
The Scottish government claims the Budget could leave Scottish families £700m worse off a year.
Social Justice Secretary Alex Neil criticised what he called "inexcusable" plans to overhaul the tax credits system.
Scottish Secretary David Mundell challenged the SNP to start working on new devolved welfare policies and stop looking for "contrived complaints".
The comments come ahead of a key joint ministerial meeting at Westminster.
Mr Neil said Scottish government analysis had found that households with the least money would face the biggest losses.
He said: "By cutting tax credits, households across Scotland will be faced with nearly £700m cuts and additional worries and stress about caring for their families.
"At Monday's meeting of the Joint Ministerial Working Group on Welfare, I will urge the Secretary of State for Scotland to call a halt to the UK government's inexcusable attack on low-paid families."
Martin Crewe, director of Barnardo's Scotland, said: "The UK government's plans to cut tax credits to working people will make it an even greater struggle for those who rely on them."
But the Scotland Office said welfare provision in Scotland was about to become a "shared space" where both governments "must work together".
Mr Mundell said: "If we are to provide the best possible service for people then Holyrood ministers need to start sharing their plans instead of looking for contrived complaints on the process.
"What new benefits are you planning? Which existing benefits do you want to top up? How are you going to pay for it?"
The Joint Ministerial Working Group on Welfare is jointly chaired by Mr Mundell and Mr Neil.
It was created to oversee social security and work programme powers being transferred to Holyrood.