I actually have a pretty similar approach. (To be honest, Civilization&#x27;s economic system is not exactly novel.)<p>Except I combine the daily rate with a running treasury (each day starts with the previous day&#x27;s ending balance). All expenses must be paid out of the treasury, so if I want to purchase something I have to save up for a while.<p>Importantly, the &#x27;treasury&#x27; is separate from my actual savings, which are deducted at a constant rate from my daily income.<p>The really fun part comes with estimation: I have several years of data now, so I&#x27;ve been able to develop a pretty complex spreadsheet which predicts my network over time. Every month I compare where I thought I was going to be and where I&#x27;m at, adjusting estimates to get more accurate over time. It&#x27;s gotten to the point where I can pretty reliably predict my net worth to within $100. (One time, I even got it right down to the cent, from 6 months out.)