Middle-income ACT householders paid an average $1594 during 2017-18 for gas. Even low-income earners with a concession paid a nation-high $1292, according to the Australian Energy Regulator report released on Thursday.

This represents an average 2.5 per cent of ACT consumers' annual income, the second-highest proportion in Australia.

Notably, the report revealed the ACT has just one gas distributor - ActewAGL - and three retailers whereas neighbouring NSW, which has four gas distributors and 11 retailers, had the second-lowest median gas bill per household in the country behind Queensland.

The ACT had the nation's smallest number of customers - 124,186 - to amortise the cost of supplying the gas but to offset this, Canberrans are big gas users with an average annual consumption per customer of 42,078 megajoules, just behind Victoria's 57,064Mj.

By contrast, electricity bills in the ACT compared much more favourably with those across the rest of the country. Canberrans paid the second-lowest annual power bill in the country during 2017-18; an average of $1803 for middle income earners and $1502 for low-income earners with a concession.

Victorians enjoyed the cheapest power in Australia with an average annual bill of $1559 while Tasmanians, with just four retailers to choose from, are hit the hardest, paying an average $2406.

The average customer in the ACT used 7009 kilowatt hours of electricity per year, the second highest usage nationally behind Tasmania.

The average electricity bill in the ACT took a significant leap during 2018, rising $332 over 2017.  Between 2016 and 2017,  the average ACT power bill rose only $82.

Across the country only South Australians were hit harder by a power price rise, paying $355 more than last year's average.

Nationally, energy disconnections increased by 7172 in 2017-18, and more people (1.1 per cent of electricity customers and 0.7 per cent of gas customers) are going into hardship programs.

The "Big Three" of Australia's energy companies - AGL, Origin and Energy Australia - dominated the market, supplying 69 per cent of residential electricity and 86 per cent of residential gas.

However, smaller companies are gaining ground and the market is becoming more competitive with between 5 to 8 per cent of customers switching retailers every quarter.

AER Board member Jim Cox said that energy became less affordable generally in 2017-18 and too many customers remained on expensive standing offers from their energy companies.

"The best way for customers to save money is to shop around," Mr Cox said, adding that the regulator provides an online price comparison website to make that task easier and which reduces the complexity of comparing market offers.

"Our work on a default market offer will provide these customers with savings."

He also urged people who were experiencing difficulty paying their gas or electricity bill to seek help before the debt gets out of hand.

"Retailers are required by law to offer assistance to customers who find themselves in [financial] hardship," he said.

After some retailers were detected during the year providing inaccurate performance data, the regulator vowed to increase its scrutiny of those businesses and said it would "take action where necessary".