Amounts reported in box 12 would not usually be other income. The box rows are labelled a, b, c, but they do not indicate meaning of the amount. Instead, there's a code listed next to the amount, which indicates the purpose of the amount.
Usually, box 12 is reporting some type of pre-tax employer fringe benefit. These amounts are not usually considered other income. For information on the code meanings in box 12, see below:
https://ttlc.intuit.com/replies/3300234
