Western Australia will burn through its existing borrowing allowance within two months, as declining revenue continues to take its toll on the state's finances.

Treasurer Mike Nahan said the state would have exhausted the amount it was authorised to borrow by the end of October, as he made the case in Parliament to allow a further $1.7 billion in loans.

The newest loan bill, flagged by the ABC earlier this month and introduced to State Parliament today, comes little more than a year after the Government received parliamentary approval to borrow $8 billion to cover general expenses.

That previous bill, introduced last April, was supposed to allow sufficient borrowings to cover the period until June 30, 2017, but Dr Nahan said further revenue writedowns had changed that.

"Unprecedented write downs in revenue have continued, we are now entering the third consecutive year of contracting annual revenue with a total of $9.3 billion reduction estimated over the period from 2015-16 to 2018-19 since the 2015-16 budget was finalised," Dr Nahan told Parliament.

"The Government has introduced further savings to address the weaker revenue outlook.

"Unless we were to make unsustainable cuts to services or pass the burden to households or businesses, these measures clearly cannot make up for the continued contraction in revenue."

Spiralling debt has become a major headache for the Government, with it forecast to reach $33 billion next year and exceed $40 billion by 2020.

Dr Nahan said $500 million of the $1.7 billion loan authorisation was needed to cover forecast general expenditure, with $1.2 billion built in as a contingency.

The Government is required to seek parliamentary approval for its borrowings, doing so by passing legislation authorising it to borrow up to a certain level.

Labor leader Mark McGowan told Parliament the need for another loan bill was an example of the Government's disintegration.

"The state of WA is going to run out of money in October if these laws aren't introduced and we are at the end of August," Mr McGowan said.

"What a shambles of a government, what a hopeless government, that we are now in this position.

"Every single Liberal and National minister is responsible for this shambles."