Disconnections for non-payment of bills are also up in recent months
There has been a notable increase in the number of domestic electricity customers falling into arrears since the end of the Government's Emergency Electricity Credit in March, according to an updated report from the Commission for Regulation of Utilities (CRU).
The numbers of domestic gas customers falling into arrears has also been rising.
Disconnections for non-payment of bills are also up in recent months, after the ending of a moratorium on disconnections in March.
Domestic energy costs have become a major burden in many households as costs soared last year and remain high.
The CRU figures show the number of households in arrears with electricity and gas bills have been increasing since the beginning of the year.
In June, 11% - or 256,000 electricity customers - were in arrears, up 72,000 since January, while gas customers in arrears rose by 24,000 to 168,000.
After a three-month moratorium on disconnections at the beginning of the year, the number being cut off for non-payment of bills has increased.
Fifteen electricity customers were cut off in April, 132 in May and 145 in June.
Twenty-one gas customers were disconnected in April, 197 in May and 202 in June.