A slowdown in GST revenue as shoppers shut their wallets is giving fresh impetus to the Reserve Bank to drive ahead with cuts to official interest rates while forcing the Morrison government to rely on workers and their superannuation to repair the budget.

A breakdown of Finance Department budget figures reveals GST revenue, a barometer for the health of consumers, is running behind the government's most recent forecasts in a development that will also hit the bottom line of every state and territory.

GST collections are now falling behind forecasts, a sign shoppers are closing their wallets. Supplied

To the end of April, the Commonwealth had collected $56.8 billion in GST. Annual growth in GST is now at 0.9 per cent, the lowest rate in almost four years and well short of inflation.

It's $630 million short of what was expected at the time of the mid-year budget update released in December.

Over March and April, which takes in the Easter period and school holidays, less than $10 billion was collected. Over the same months last year GST raised almost $10.5 billion.

The drop in GST came despite the national population increasing by almost 400,000 and total employment lifting by 316,000.

GST revenues for the 2018-19 financial year started well but have slowed through the past 10 months as consumers wind back their spending. Through the March quarter, the volume of retail sales contracted in a development that will hit the national accounts which will be released on June 5.

While GST revenues are falling, total PAYG tax collections are lifting on the back of the solid jobs market. Superannuation taxes through April reached $10 billion, the highest they have been since the same period in 2008 and a reflection of the lift in the Australian sharemarket over recent months.

Financial markets now fully expect the RBA board to cut rates at its meeting next week and to follow that up with another cut by October. That would take the official cash rate to a record low of 1 per cent.

CommSec chief equities economist Craig James said while the overall budget figures showed the nation's finances improving, the drop in GST pointed to broader issues that meant a rush to surplus might cause economic problems.

"That means a small deficit is more appropriate than a blinkered approach of keeping the budget in balance or pushing it further into surplus," he said.

"Businesses and consumers are still spending, but at a far slower rate than late last year."

Prime Minister Scott Morrison confirmed on Sunday the government would take its full package of tax cuts, which included major reductions for high income earners from the middle of 2024, to the Parliament for approval.

Prime Minister Scott Morrison said planned tax cuts would help boost confidence and the economy Alex Ellinghausen

He said those cuts, alongside the expanded low and middle income tax offset which will deliver up to $1080 for people earning less than $90,000, were important for the economy.

"They are good measures, they will be good measures for the Australian economy, good measures

for jobs, and good measures for confidence in the Australian economy as we face what are some

difficult headwinds in the years ahead," he said.

It follows an update by the OECD on the state of the global economy, downgrading all its expectations because of concerns of a deeper-than-forecast drop in international trade.

The organisation believes the global economy will expand by 3.2 per cent this calendar year, well down on the 3.5 per cent it had predicted in March.

Australia, due to its heavy exposure to global trade, is one of the worst hit with the OECD tipping the domestic economy to grow by a downwardly revised 2.3 per cent through 2019.

It is forecasting the economy to grow by 2.7 per cent in 2020, in line with the Reserve Bank's most recently revised predictions.