(((((Renee))))) Does a single call after a month mess things up? Probably not. Does a call, an voicemail, an email, and a text, all on the same subject mess things up? Probably yes.
Cold turkey. You can do it.
Last April, I decided to give up Coke. (The soda! ) I drank at least two 20 oz. bottles every weekday, sometimes more. At first I thought I would cut to one a day, but I immediately decided to just not have another one. I've been tempted since then (a picnic with glass bottles on ice, the Coke machine giving me a Coke when I asked it for water), but I haven't had a single soda of any kind in over a year now. It was hard, especially at first. I thought, what could one hurt... But, I didn't do it. If I can do that, I think you can do this. Just make the decision to not cantact him. At all.
For an issue like the taxes, I'd be tempted to write a letter. That way you can't get sucked into the drama. The only other exception would be a real emergency. I mean the life threatening kind. Other than that, prove to yourself, and to him that you can take care of yourself. You can be independent. You don't NEED him, or any other man! YOU CAN DO IT!