The number of Australians struggling to make home loan repayments has surged by 627,000 over the past year, to an estimated 1.43 million borrowers, according to analysis by researcher Roy Morgan.

This represents 28.8 per cent of all mortgage holders – the highest number in 15 years – and follows the Reserve Bank’s dozen rate increases since last May to take the cash rate to 4.1 per cent, its highest level since May 2012.