Tuesday’s federal budget will forecast a surplus of $9.3 billion for this financial year, after which the bottom line will plunge into successive deficits that will be larger than forecast six months ago.

The surplus for 2023-24, which is an increase from the $1.1 billion deficit predicted in the mid-year economic and fiscal outlook released in December, will disappear from 2024-25 as the government deals with “unavoidable spending” and spends big on its Future Made in Australia Act.