I sell services to bizs to help them get more customers and therefore make more money, I charge them a monthly fee for my services. One of my clients (car towing business) lies to theAustrailia tax office about his income, so that he doesn't have to pay high taxes - is my service helping in haram?

Ustadh AbdulAziz al-Haqqan

What he does with his business is not a sin upon you, as long as you don't help in this.