MINING royalties and house sales stamp duty are two of the big variables in any NSW budget, because of changes in coal prices and exchange rates in terms of royalties, and the state of the housing market when it comes to stamp duty.
Treasurer Dominic Perrottet acknowledged in his budget presentation on Tuesday that stamp duty takings were down, and royalties were up, and Budget Paper No 1 provides the financial detail.
The government had originally expected to earn $1.665 billion from coal royalties but took an extra $111 million, taking the total to $1.776 billion.
A table of revenue "sensitivities" - the way that market changes affect government revenues - looks at what happens when there is a 1 per cent change in volumes, prices and exchange rates.
Every one per cent movement in predicted export volumes is expected to add or subtract $17 million from the budget bottom line. A one per cent movement in prices, measured in $US, equates to an $18 million change.
Similarly, for every cent movement in the $A-$US exchange rate, the budget position changes by $18 million.
The government had originally budgeted to take $11.46 billion in stamp duty, but this has been revised down by $961 million to $10.49 billion this financial year. The reasons were lower than expected growth in property market transaction volumes and prices and a significant shift away from investors to first home buyers.