Check with your specific town office for individual deadlines. Porter, for instance, has notified the public that dog licenses are due by January 1, 2020.
All dogs six months and older must be registered in the town in which the owner resides. It's simple, inexpensive and can save you money in fees as well as help to return your beloved pooch home should he ever wander away.
When you register your dog at your local town office bring with your their rabies certificate (there is a rabies clinic on 1/4/20 from 8-11 am at the Brownfield Town Office), and spay/neuter certificate if applicable.