What we already know about the budget

WHAT WE KNOW SO FAR ABOUT TUESDAY'S BUDGET

* Economists predicting MYEFO forecast of $31.2b for 2015/16 deficit to blow out to upwards of $40b.

* Treasurer Joe Hockey promising "quality trajectory back to surplus". But no surplus likely in the forward estimates.

* Fall in iron ore prices to impact on tax receipts for 2015/16

* Record infrastructure spend, as states take advantage of asset recycling scheme bonus payments

* Crackdown on welfare cheats through better data matching to identify fraud. Centrelink computer upgrade worth $1b to help with this.

* Major $3.5b reform to child care, with single payment paid directly to childcare centres to reduce parents' upfront costs. Stay-at-home parents with a family income of more than $65,000 will no longer secure childcare subsidies.

* Income-tested hourly subsidy for nannies for 10,000 shift worker families in a two-year trial costing $246m.

* Loophole that allows new parents to claim paid parental leave payments from both the federal government and their employer set to be closed, saving nearly $1b a year.

* Plans for a $20b medical research fund to go ahead

* Pharmaceutical Benefits Scheme changes to save about $3b over four years, and comes via removing subsidies from a raft of over-the-counter medicines. Health savings likely to total $7b over forward estimates.

* Government to fund $1.3b worth of new generation cancer drugs over four years through listing on the PBS

* $6 bonus for doctors to prompt parents to immunise their children to be doubled to $12. Objectors to immunisation will not be eligible for welfare and childcare benefits.

* Almost $300m for mental health services

* $200m for dental health care

* No changes to superannuation this term

* Tighter access to age pension. Part-pension assets test (excludes family home) to be cut to $820,000 for couples.

* $128m over four years for a financial crimes task force

* Global companies to face tighter laws on shifting profits to foreign tax havens. First tranche of this is expected to reap money in forward estimates.

* Tax cuts for business. 1.5 per cent for small business.

* Drought package including $250m for the drought concessional loan scheme in 2015-16 and $35m to boost economic activity in badly hit towns and regions.

* An extra $40m to upgrade airstrips and boost air services for remote communities.

* $100m for car industry assistance

* Annual pay rise lifted to two per cent for Defence workers, costing $217m over four years.

* Fourth round of government agency abolitions and mergers and more assets eyed off for sale, including Australian Rail Track Corporation.

* GST imposed on overseas digital downloads, raising $350m over four years

* Crackdown on 30 multinational companies seeking to avoid tax.