Are you able to be in the Marines with a tattoo on your forearm?
Yes you can. They mark down all the tattoos you have when you join. Once you do join though they don't allow you to get any new ones that are visible, which is why they record all of your previous tattoos.
However, there is not much they can really do if you do get one. Some commanding officers or higher ups are very strict about that kind of stuff and some aren't.
My older friend joined the marines and he has a tattoo on his chest and he told me they were very tough and strict on him
they are very strict on tattoos...you would have to cover it up..like buy foundation or something and cover it.