So I am an h-1 visa student - which I am liable to for all taxes (right?)

I recently had a talk with my accountant and I didn't understand what he was saying.

I've been filing my taxes as single 3 but he had told me that I needed to change to single 0? Because I was paying too little taxes?? Could anyone please explain the difference?

Just to give you some info. I am single person working in US, all my family is in another country.

Help me please

Thanks

"...filing my taxes as single 3...". What does this mean? Are you claiming 3 allowances on your W4?
Have you been filing your tax return?

As a foreign national on a H-1 visa, you are REQUIRED to claim SINGLE status with ZERO or ONE exemption, no higher. This is to ensure that enough taxes are withheld from your salary to cover your income tax liability and to give an incentive to file your final tax return after you return to your home country.

So claim SINGLE with ONE exemption and get on with your life.