I am moving from Australia to the US in August 2010 and I will be employed on full-time basis by a US company.

I am receiving a bonus payment on arrival in the US. I have been told that this bonus payment is treated differently at tax time since I will have been a non-resident alien for less than 180 days as of Dec 31 2010.

My understanding is that if the bonus was paid in January 2011 and I remain in the US for longer than 180 days after that time then I would pay less tax (or: receive a partial refund of tax withheld) than if I receive that bonus in 2010.

Is that true? If so can someone please point me to the relevant IRS statute so I can convince the US HR department to delay bonus payment until 2011 (if possible).