Resonance states of BF- are studied with high-level ab initio methods. In analogy to the fundamental anions N-2(-) and CO-, the (2)Pi ground state of BF- has been found to be a short-lived shape-type resonance state exhibiting a lifetime of less than a femtosecond. In contrast, the lowest quartet state (4)Sigma(-) of BF- is clearly long-lived, since the decay channels via direct electron emission and dissociation are closed and all other possible decay channels are spin-forbidden. The lowest sextet state of BF- is also investigated. Connection to recently identified long-lived high-spin states of N-2(-) and CO- is made and their relations are discussed.