Earlier quoted context omitted.
Only if you don't use the room for anything except work. You've got a computer in there that you're also using for private stuff? Not tax-deductible anymore. Private books on the bookshelf? Not tax-deductible anymore. You've got a wardrobe with some clothes you're only accessing once per season (to store off-season clothes)? Not tax-deductible anymore.
Like you will declare those...
But you just have to love how HN endorses tax fraud.