There are strong regional variations across Britain, with mothers in the South West having to work for almost 19 weeks a year before the cost of a childminder or a nursery is covered – compared with just over 15 weeks for mothers in the West Midlands, according to mutual Family Investments.
In Scotland, mothers have to work just under 17 weeks to break even in their costs.
The findings are based on a mother having one young child and having no childcare help from relatives or Government schemes to help working parents.
On average, the study found a mother pays £7127 a year to a childminder or nursery and would need to work for 17 weeks a year before she has broken even on these costs.
The research used average childminder and nursery costs taken from local authorities as well as regional earnings figures from the Office for National Statistics.
London was found to have the highest typical annual childcare costs, at £9283 –but London mothers also had the highest average wages at £15.07 an hour.
Parents are entitled to increased levels of help with childcare costs after their child's third birthday, with 15 hours a week of free early education.
A Government voucher scheme also allows mothers and fathers to pay for costs out of their pre-tax wages. Basic rate taxpayers can pay for up to £243 of childcare a month with the vouchers. The study assumed parents were not taking part in the voucher scheme.