The federal government would more than double its revenue if it increased the consumer tax to 15 per cent and cut almost all exemptions, independent modelling has revealed.

A total of $130 billion in revenue would flow to the government’s coffers in 2017-18 under the GST increase, amounting to an extra $65.6 billion, according to the non-partisan Parliamentary Budget Office (PBO).

The 15 per cent rise would expand the tax to fresh food, education, healthcare, water and sewerage, childcare and private health insurance, all of which are currently exempted.

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The PBO crunched the numbers at the request of Nationals MP David Gillespie, who is expected to propose a GST increase in a speech on Thursday.

“[New Zealand] seem to be going from strength to strength in their economy,” Dr Gillespie told ABC’s AM program.

“They have it applying to about 97 per cent of consumption in their country and we only have it on 47 per cent.”

The GST rise could be coupled with a drop in personal tax, equating to up to $28 billion.

According to News Limited, all tax brackets could see change. Earnings between $100,000 and $180,000 could be cut from more than 40¢ to 30¢, while the lowest earners – who take in between $18,200 and $35,000 – could see a 4¢ drop to 15¢.

Treasurer Scott Morrison said rumours of GST change were “speculative”.

“The federal government is ­involved in good-faith discussions with the states and territories on how we can work together to ­improve our tax system,” he told The Australian.

“The commonwealth and states and territories continue to explore options for improvements to the tax system.

“This ­includes ­reviewing the operation of all state and commonwealth taxes to achieve a better national tax system.”