A lot of budgeting fails not because of math but because of human decision-making. That’s where behavioral design meets spreadsheets: strategies that reduce friction for good choices and add friction to poor ones tend to work best. Automation of regular payments and savings (so they happen without a monthly decision) is a classic nudge; another is defaulting to lower-risk options, like direct deposit splits that allocate funds to retirement automatically. Other techniques include commitment devices (locking money into accounts that are costly to withdraw), commitment savings products, and timed rules (e.g., wait 48 hours before large discretionary purchases). On the flip side, too many daily micro-decisions about small purchases create decision fatigue, increasing the chance of impulsive spending. Designing a budget around a small set of automated rules reduces cognitive load and supports consistency over the long run. The next question asks which single tactic most clearly reduces decision fatigue in a household budget.