This is a very easy cocktail to make at home but not that easy to find out and about. Even if you were to come upon a bartender who knew of what you speak, the chances of fresh oranges, squeezed at the bar, may be slim. But do try it if you find yourself at a haute cocktail lounge.
A note on the great Angostura Bitters stand-off: (Actually it deserves more than a note, probably a whole column, but this will have to suffice — I have to do my taxes.) Earlier this year, there was a worldwide shortage of this certain type of bitters that sent ripples through the bartending world. Due to a rift between the House of Angostura in Trinidad and its bottle supply company, production of Angostura Bitters stopped between November and February. People were frantically trying Fee Brothers aromatic bitters or The Bitter Truth brand bitters from Germany — both worthy alternatives but not the household name we know. Things are back to normal or so I've heard, and that's a good thing for hangover remedies that require ginger ale and Angostura Bitters, but you still might find the singular bottle scarce on some shelves.
Some old bartender guides will name the Income Tax Cocktail as the Maurice. Now the question remains: is it Morris as the British pronounce it or Maurice as Steve Miller deems it? Well, he is the pompitous of love, whatever that may be. My recommendation for how to order? Drop the Income Tax moniker. It brings up too many bad memories. Order a Bronx with Bitters and set a trend in motion.