You will need to declare the income within a set period of earning it (14 days). If you and your partner haven't worked for a long period of time, you will accumulated working credits, and it is highly unlikely that 7hour work would impact your payments at all. You would need to adjust your estimate to include that money. And if the employer deducts tax (many will automatically do it) you would need to lodge a return to get back anything you've paid in tax (etax is great for that).