H-1B: This is a speciality occupation visa and is one of the most popular work permits. However, it is very limited during the year when you can apply.
L-1A: This is the intracompany transferee visa and is allowed when you already have a company in your country and want to open a branch office. The investment required for this visa is much less than many other types of visas.
E-2: This is the Treaty Investor Visa and allows people from certain countries to come to the U.S. and both invest and open their own business. It is a very nice work permit.
O-1: This is known as the extraordinary alien petition. It is difficult to obtain, but depending on the type of work you will do, will depend on what burden of difficulty you must show. If you have years of experience doing something and H-1B’s are used up, this is a good alternative.
P-1: If you belong to some type of performing group or an entertainment group or physical activity group, this could be the work permit for you.
B1: This is a very short type ‘work permit’ which really allows you to come into the U.S. for a very short period of time to do work for your foreign company. It does not permit you to work or get paid inside the U.S.
R-1: This allows you to work in some type of religious capacity in the Church or some designated religious organization.
U-1: While this is technically not a work-permit, you are allowed if you get the U-1 to work. This is meant for those who are the victims of certain crimes.
S-1: Just like with the U-1, this particular visa is not by itself one that is a work permit. However, if you qualify and are a material witness, you can work with the S-1.
T-1: Like the U-1 and S-1, this by itself is not a work-permit. It is meant for victims of trafficking. However, you will be allowed to work if you get the T-1.