When is smallmouth bass season?

Question way too short & very unclear.  If you're asking from a legal point of view, some states may have only certain times Smallmouth Bass can be caught.  Others...it might be open all 12 months.

If you're asking what's the best time of year, IMHO it's the fall and/or early winter.  When either Largemouth or Smallmouth get a freezing night followed by a warming trend, they go into a feeding frenzy.  They know winter is coming & start gorging themselves.    

That depends on where you want to fish.

Smallmouth Bass season ended  yesterday where I  live. It might be open where

you live.

Where I live- 3rd Saturday in June thru Sept.