How long before my boyfriend can come back here in the US if he just got deported a year ago?

The answer to your question depends upon the reasons your boyfriend was deported and also your immigration status. It would also depend upon whether he was ordered deported or removed (it is an important legal distinction). Assuming he was ordered removed, he cannot re-enter the United States for 10 years. He would also likely be barred for 10 years due to being illegally present in the U.S. for more than a year. These bars can be waived if you can demonstrate extreme hardship and you are a U.S. citizen or lawful permanent resident. This requires you to be married and petition for him. You must then show extreme hardship to you if he is not allowed to enter the U.S. before 10 years.

It is important that you meet with an attorney in person. Bringing a person back after deportation is complicated and requires filing the right forms and supporting evidence. It is also requires knowing whether the person is eligible to return. Before you take any steps, you should consult with an attorney.