In her speech to the party conference in Perth today she will compare the policies of the SNP in Government to Chancellor George Osborne at Westminster in the week he delivered his budget.
Ms Lamont is expected to say: "Seven years of nationalism and not one policy which redistributes wealth from rich to poor, in fact the opposite. Those in the richest houses saving the most, those with the most getting more, those with the least getting less.
"That isn't just a betrayal of social justice but a betrayal of everything we believe Scotland stands for."
Ms Lamont who this week revealed the party's plans for a devolved Scotland after a no vote in September, including allowing Holyrood to increase the top rate of tax but not lower it without also reducing the lower rates said the SNP plans would benefit the rich.
She is due to say: "Social injustice is what puts Scotland at its greatest disadvantage and restoring the 50- tax rate will start to fight injustice.
"We have a nationalist Government which refuses to reverse Tory tax cuts for millionaires and votes against giving workers on government contracts the living wage. Forget indy lite, this nationalist government is Osborne max."