Rot & Ruin by Jonathan Maberry

In the zombie-infested, post-apocalyptic America where Benny Imura lives, every teenager must find a job by the time they turn fifteen or get their rations cut in half. Benny doesn't want to apprentice as a zombie hunter with his boring older brother Tom, but he has no choice. He expects a tedious job whacking zoms for cash, but what he gets is a vocation that will teach him what it means to be human.