A proposal to expand state sales taxes by Gov. Mary Fallin would draw its largest share of new revenue from Oklahoma's residential electric and natural gas customers.

Fallin's plan would end an exemption of the state's share of sales taxes on utility services for residential customers. Those sales taxes are currently only paid at the city and county level by residential customers.

Expanding the state sales taxes to residential utility service would increase monthly bills by 4.5 percent. The average Oklahoma residential electric bill is $111 per month, according to the federal Energy Information Administration.

If the Legislature agrees, the proposal for residential utility sales could raise an estimated $132.6 million in new state revenue in the 2018 fiscal year, according to data from the Office of Management and Enterprise Services. That would rise to $137 million in fiscal 2019 and $141 million by 2020.