There is certainly no Federal law that you have to sign up for COBRA if you don't want to. However, technically if you don't want it you should tell them so. While I doubt that the DOL would come after you for refusing to sign the declination form, I honestly can't come up with any reason why, if you know you don't want the COBRA, you shouldn't just sign the thing and send it back. If you change your mind within the 60 days the law gives you to make the decision, the fact that you initially declined it will NOT prevent you from later accepting it.