The SNP has been accused of failing to eradicate fuel poverty “by a country mile”.
The Housing Act requires the Scottish Government to stamp out the scourge of punitive energy costs by November 2016 “so far as reasonably practicable”.
But despite that date being reached, more than 800,000 families are still struggling to heat their homes.
The problem is particularly acute in the islands, where energy consumption can be more than double the national average and annual bills can be £300 higher.
It is also exacerbated by a controversial electricity surcharge on homes in northern Scotland, which the Press and Journal and local politicians have campaigned against.
The failure to meet the November 2016 target has led to a backlash from opposition parties, but Housing Minister Kevin Stewart said the administration remained “absolutely committed” to tackling fuel poverty.
Scottish Liberal Democrat energy spokesman Liam McArthur MSP said: “The SNP government has missed its statutory responsibility to eradicate fuel poverty by a country mile.
“Hundreds of thousands of families across Scotland are still wondering how they are going to afford a warm home this winter.
“Despite the overwhelming evidence to the contrary, ministers spent the months running up to the election denying that the target was going to be missed and even lowered spending in this area.
“They were frozen to the spot instead of working with other parties on a fresh strategy to establish warmer homes.”
Scottish Labour Housing spokeswoman Pauline McNeill added: “No one should have to choose between being able to eat or being able to heat their home.”
Both Orkney MSP Mr McArthur and Ms McNeill added that a Warm Homes Act would help tackle fuel poverty.
More than half of the million residents in rural Scotland suffer from fuel poverty – rising to two-thirds of homes in remote areas, according to the latest figures.
In October, two reports made more than 100 recommendations on how to tackle the “shocking” and “simply unacceptable” levels of fuel poverty in Scotland.
Mr Stewart said: “We remain absolutely committed to tackling and as far as possible eradicating fuel poverty in Scotland and have already designated home energy efficiency as a national infrastructure priority.”
More than £650million had been allocated to tackle fuel poverty since 2009, he added.
“Despite our efforts, above-inflation energy price increases that are beyond our control have greatly impacted on
Scottish households,” Mr Stewart said.
“We are committed to introducing a Warm Homes Bill during this parliament to help tackle fuel poverty.”
