The NSW government is putting forward an amendment bill that could allow foreign-owned developers to qualify for upfront exemptions to stamp duty and land tax rises outlined in the June budget.

In the June state budget, Treasurer Dominic Perrottet announced that the existing stamp duty surcharge for foreign property investors would be doubled to 8 per cent and the land tax surcharge would be lifted from 0.75 per cent to 2 per cent.

The budget papers said foreign-owned developers based in Australia would be entitled to a refund if they sold the property within five years, but those refunds were not enacted.

The decision to consider upfront exemptions has arisen from concerns that foreign-owned developers, such as AV Jennings which is owned by Singapore-based SC Global Developments, could be put at a disadvantage which could affect the supply of new property in NSW.

The proposed changes also extends the time frame in which developers must complete their development from five to ten years, as the time developers sometimes require to meet planning approvals and other requirements make five years unrealistic, according to finance minister Victor Dominello.

The Sydney Morning Herald reports that Dominello says the proposed changes have been made following discussions with the industry which "suggested that additional flexibility would be beneficial, without encouraging land banking or weakening incentives for timely development".

The new laws will be debated in NSW parliament in the coming weeks.

Read more about the NSW state budget:

Housing measures in the 2017 Budget

NSW budget fails to deliver: REINSW

NSW budget does little to improve housing affordability