Cash for down payments

[Andre Olsen]

Hi all, 

Hopefully posting in the correct place (newbie). 
my partner and I are looking at investing. We make 120k gross income and an additional 50k in cash tips. Couple questions: 

1) Can we use cash for down payments? 
2) if yes, do we have to pay taxes on the cash we use? 

Basically we want to avoid paying taxes on the cash tips we receive but would love to use it as a down payment. 

Thanks for you inputs, 

Andre