4a317c29_lian_Broadcasting_Corporation___Definition
[Term] Wage price index [Definition] 
Measures the change in wage levels paid to employees. Important to the budget because higher wage growth across the economy means faster growth in income tax revenue, which can be magnified by bracket creep – individual income taxes (which includes non-wage related capital gains tax) make up around 46 per cent of federal government revenue. Higher economy-wide wage growth may also mean larger rises in public service pay, but the income tax boost to the Government far outweighs this cost.
Budget 2014: Deficit tax may raise a lot less than Treasury forecasts says analyst - ABC News (Australian Broadcasting Corporation)
Definition