Saskatchewan's crown power corporation says bills are expected to jump slightly as the federal carbon tax begins to appear on customer's bills.

While the carbon tax was officially in effect as of Jan. 1, 2019, SaskPower bills didn't start including the tax until April.

SaskPower waited until this month to begin collecting the tax as it was still waiting for final details on how the tax would be applied to different generation sources, like coal or natural gas.

SaskEnergy started collecting its tax as of April 1. The natural gas utility is not classified by the federal government as a carbon emitter and falls under different rules.

A residential customer can expect to pay an additional $18 per year for the tax. The tax for the first three months of the year will be evenly spread out over future bills for 2019.

SaskPower customers can expect to see a small increase on their bills as the crown utility retroactively charges the carbon tax back to January. (Michael Bell/Canadian Press)

The crown utility said the tax will appear as a separate line item on any upcoming bills.

Information about the retroactive increase appeared in customers' bills in March.

SaskPower expects the cost of the carbon tax will rise to $63/year for residential customers by 2022.