Some certainty for internet providers when it comes to broadband pricing.

The Commerce Commission has decided on a backdate for the new, higher price it's allowing Chorus to charge for copper broadband.

It says higher prices can be backdated to December 1, but no earlier.

Spark was the first to move after the cost hike, announcing price increases for its customers will take effect from February.

The company had expressed concern that backdating could jeopardise any future price stability.