Requirement for the length of a HMAC tag?

I've seen NIST requirements about key length. What about the output lengths ?

Is 112 bits enough for the HMAC output length ? Can we truncate the tag to keep only 112 bits ?

• Why do you consider collision resistance in the context of a MAC? I don't think this is relevant. AFAIK you get $n$ bits of security from a good $n$ bit MAC, and neither collisions nor multi-target attacks apply, assuming a sufficiently long key. – CodesInChaos Dec 1 '14 at 10:38