Can you nominate month to end the US tax year when moving overseas?

Hi, we left CA June 30 to relocate back overseas (Australia) permanently. However, my husband is still employed with US company until August.  Our rental contract ended June 30 as well. Can we nominate the US tax year to end on a certain date? For example, when we left on June 30 or when his overseas employment ceases in August? or is there any benefit to being taxed the full year until December 31? Please advise