North Ayrshire and Arran MP Patricia Gibson has challenged Prime Minister Rishi Sunak on inflation and the cost-of-living crisis.
And the PM admitted that inflation was putting pressure on family budgets.
At Prime Minister's Questions on Wednesday, the SNP MP asked: "As inflation continues to outstrip pay awards, and tomorrow we expect to see the 13th consecutive rise in interest rates, will the Prime Minister tell the House by how much living standards have fallen during his eight months in office?"
Mr Sunak replied: "I have always been very clear, inflation is putting pressure on family budgets and that's why the UK Government has taken decisive action to support families through this difficult time, including households in Scotland, who are receiving considerable support not just with their energy bills, but also the most vulnerable as well."
Ms Gibson said later on Facebook: "As inflation continues to outstrip pay awards and interest rates are set to rise tomorrow for the 13th consecutive time, I asked the Prime Minister today to explain by how much living standards have fallen in the eight months since he entered Downing Street.
"Predictably, he was unwilling to do so."
In the same debate, the SNP's Westminster Leader accused the Prime Minister of taking his "honesty lessons from Boris Johnson".
Stephen Flynn told the Commons: "In February, the Prime Minister told this here House that borrowing costs are back to where they should be, in March he boasted we are on track to halve inflation by the end of the year, and in May he then said economic optimism is increasing.
"Given the dire economic reality of today, is it not now clear that he has taken his honesty lessons from Boris Johnson?"
Mr Sunak replied: "He also failed to mention that not just the Bank of England, not just the OBR, not just the OECD, but also the IMF, all of them have upgraded their growth outlook for the United Kingdom economy this year.
"Whilst he and others were predicting this country would enter a recession, the actions of this Government have meant that we have so far averted that and we continue to be on track to keep reducing inflation because that is the right economic priority."
Commons Speaker Sir Lindsay Hoyle warned Mr Flynn to be a "little bit more cautious" and not imply Mr Sunak was misleading MPs.
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