Plans to change tax credit entitlement that would have cost couples with disabled children up to £3,870 a year have been altered.
Millions of working low-income families can claimtax credits, in addition to some benefits.
Changes in April mean couples with children will have to work for 24 hours a week between them, not 16, in order to qualify for working tax credit.
However, the government has now made carers exempt from this change.
From April, the general rule is that couples will have to work at least 24 hours a week, rather than the current threshold of 16 hours, to qualify for working tax credit. One must work for at least 16 hours a week.
However, a couple, in which one of the partners is a full-time carer and in receipt of carer's allowance, will be exempt from the change.
So these couples can continue to receive tax credit support if just one of them works for at least 16 hours. Such couples will also be able to claim for childcare costs through the tax credits system.
The move comes following pressure from a number of charities, which said they were "delighted" with the decision.
"Couples with disabled children, who have to divide their time between caring for them and earning for the whole family, will find that a considerable burden and worry has been lifted from their shoulders," said John Andrews, chairman of the Low Incomes Tax Reform Group.
"Without this relaxation,they would have faced losing up to £3,870 a year they could ill afford.
"While we very much welcome this change of direction, we remain very concerned for the hundreds of thousands of other couples facing this new 24-hour restriction, particularly at a time of economic difficulty when even those in work are not always able to secure the extra hours needed to keep their working tax credit entitlement going."