The poorest 20% of households in Scotland will lose on average £520 every year until 2020.
That's according to figures released today, suggesting 800,000 Scottish homes will be hit by proposed cuts to tax credits.
Around 38,500 thousand Fife households receive the benefit, which is designed to top up low wages.
Conservative ministers say the current system is unsustainable and needs reformed.
Scottish Labour Public Services spokesperson Jackie Baillie said:
"This expert research has confirmed that the Chancellor’s plans to slash tax credits will hurt the poorest families in Scotland whilst the richest will see more money in their pocket. This is Robin Hood in reverse, taking from the poor to give to the rich.
"Tax credits work. It's why the Labour Government introduced them in the first place. They help those in low paid jobs and ensure work pays. The so called national living wage from the Tories is a sham, and it was under Ruth Davidson’s leadership that the Tories voted against extending the real living wage to more low paid jobs in Scotland last year.
"Last week Ruth Davidson had a chance to call a halt to these cuts. She failed to do so and now the poorest in Scotland will lose out. A senior Tory likened these cuts to the Poll Tax, and Ruth Davidson Should not need to be reminded of how disastrous that policy was in Scotland.
"After five years of the Tory Government and eight years of the SNP Government, the gap between the richest and the rest in our country is still unacceptably high, these cuts will only make it worse."