Households in Northern Ireland have yet to receive a £400 energy support payment despite being promised the scheme would apply across the UK.
The £400 discount on energy bills was rolled out in England, Scotland and Wales last month and was also meant to be paid to Northern Ireland customers in November.
There has been uncertainty about when that money will be paid, with NI households not yet receiving anything despite reassurances from former prime minister Liz Truss.
Her government had said it would ensure Northern Irish households received the same benefit overall as those in the rest of the UK by backdating support for October bills.
Truss said: “We will be providing the same support to Northern Ireland as we are providing for people in Great Britain.
She added: “My understanding is that will happen in November, but it will be backdated to October."
The rollout has hit difficulties as Northern Ireland’s energy market operates differently from the rest of the UK's model, with specific rules and regulations.
The energy price cap, which limited gas and electricity prices, would have a limited effect in the country as two-thirds of households rely on oil heating.
The UK government promised an additional payment of £100 to households that do not receive support through the price cap, such as those who use home heating oil.
In response to a question from Alliance Party deputy-leader Stephen Farry, the Department for Business, Energy and Industrial Strategy (BEIS) said the support payments would be rolled out this winter, but declined to specify a date.
Farry, MP for North Down, tweeted: “We need certainty and much quicker delivery. We continue to lobby.”
The Alliance Party in Westminster account added: “The timescale for the rollout of the £400 energy support payment for NI households remains vague. Instead, we have ‘this winter’, which is basically any time between now and end of February. We continue to lobby for faster progress.”
In the Commons on Wednesday, DUP leader Sir Jeffrey Donaldson pressed Northern Ireland minister Steve Baker over the region's Energy Bills Support Scheme (NI EBSS), asking: “Will the minister assure me that he will continue in his efforts with us to ensure the £400 payment is made to the people of Northern Ireland as soon as possible?”
Baker replied: “We certainly will continue in those efforts together.”
Northern Irish politicians want to offer households one-off payments rather than instalments like the rest of the UK but this has yet to be formally agreed upon.
It comes as the government is to extend a deadline for calling an election in Northern Ireland.
Northern Ireland secretary Chris Heaton-Harris confirmed the move in the Commons on Wednesday as he outlined his next steps in response to the power-sharing crisis in the region.
Watch: NI secretary confirms plan to push back deadline to hold Stormont election
A DUP boycott of the devolved institutions, in protest at the Brexit Northern Ireland Protocol, has prevented an executive being formed in Belfast.
Existing legislation gave the Stormont parties almost six months to form an executive following the last election in May, which saw Sinn Fein emerge as the largest party for the first time.
The deadline to establish a new executive lapsed on 28 October, at which point the government assumed a legal responsibility to hold a fresh poll within 12 weeks – January 19.
Heaton-Harris said he was now extending the deadline for parties to form an executive by six weeks to 8 December, with the option of a further six-week extension.