A Christchurch firm has been fined for paying a migrant worker less than $5 an hour.

Milk Distributors JP and JD Bowden Partnership charged the woman an employment premium that means she took home just $4.37 an hour.

The Employment Relations Authority has imposed a $5000 penalty.

The woman has also been repaid $8000 she was charged in employment premiums.

The woman even had to cover her own tax payments.