Interest charged on a capital gain

If I sell an IP with a contract date of say 1 July and incurr CGT, do I have to pay the ATO intrest for that year or only from the end of that financial year that I sold in?
ie: could I potentially have 364 days of interest free period on the CGT payable to the ATO? Or.... is it better to pay them the CG as soon as you get the funds from the sale?
So really youd be mad to sell on 30 June?

You'd be mad to sell at any time IMO. (but I am a long term buy & holder).

But if you have to sell then the only time June 30 would be appealing would be if you are going to earn less that year - as CGT is calculated at your marginal tax rate in the year of sale of the asset.
We sold an IP and ensured the contract was dated 2nd July. We declined the agent's kind offer to sign beforehand and he would insert the date later.

If you use an accountant or tax agent, you don't have to lodge your tax return until the end of May.

It also gives you the full year to plan. In our case the IP was in hubby's name, so he salary sacrificed the max ($100K - over 50) into super to reduce his income as much as possible to lower the tax rate. The CGT amount sat in an offset account for nearly 2 years and saved us about $9K in interest.

Therefore if you sell a property on 1st July 2010, the gain goes into the 2010/2011 tax year. You have to lodge your return by the end of May 2012, which gives you tax free use of the CGT for nearly 2 years.