Does your DS9 have things that he does that contribute to running the house? Maybe increase the responsibility a little, even something he doesn't think he can do, and have him work on it and celebrate the success. Even things I give my DD9 like opening the envelopes for the mail and sorting the paper recycling, putting bills in a pile. Not to make her worried but to de-mystify the goings-on. And she learns the categories of things we need to live, like the natural gas and the phone, etc.
For her personality this makes her less anxious - some kids it might make them more if they're going to worry.
What about a special project like looking in the paper or online for rentals, seeing how much things cost, give him a virtual "job" with a salary and have him work out how much he can spend, all that sort of thing. Make it fun and practical.
He sounds like a thinking kid and sometimes they need to be reassured of the mechanics of things for themselves in addition to reassurance via talking (I've never been one to be reassured much by talking. I really have to do stuff, even if I get it wrong and know what I need to work on...to become less anxious).
