Town clerk Denise Graffeo is reminding dog owners who have not already done so to purchase a 2012 license for their dog. Tewksbury charges a $15 fee for residents who license their dogs by a March 15 deadline. After that date, a $5 charge is added, and starting July 1, an additional $10 late charge is levied, bringing the fee to $30. No late charges are assessed for a dog six months of age or younger that is being licensed for the first time. When obtaining a license, the owner must present proof of rabies vaccination for the dog if it is not already on file. Tewksbury licensed 2,081 dogs last year and so far this year has licensed 2,093, Graffeo said.