@sjrcpa is on target about the insurance.  Prof Liability is the same as Errors & Omissions. That is you make a mistake that you're liable for....  Like failed to report a lot of income that creates a lot of P&I....

. If you have an office you also want general liability in case one of your clients falls off a chair and sues you.  

If you have employees you'd also need workers compensation.... in case one of your employees falls off a chair.... 

Call a local independent insurance agent. They'll understand the coverages and products better than you.