When the electricity and gas bill lands for Elizabeth McArthur’s Sydney apartment each month, there’s nobody to split it with. The same goes for the mortgage. And when she travels, 33-year-old McArthur has to pay the full cost of a room designed for two unless she’s travelling with friends.

These are examples of the so-called “singles tax” – the extra money unpartnered people have to pay to match the lifestyles of their paired-up counterparts. Studies suggest the singles tax, at last official count, was about 3.5 per cent, but trends in utilities and rent bills mean today singles could be paying up to 10 to 15 per cent more than their partnered friends.