The problem you've described isn't a spreadsheet limitation, it's a design question that spreadsheets were never built to answer. You want an average that respects time, that knows the difference between a month that has happened and one that hasn't. That's not a math problem. It's a logic problem. And the fact that you had to reach for EOMONTH, only to find it still required manual updates, tells us everything about where traditional tools fall short.
The core insight you're chasing is elegantly simple: a budget tracker should only average completed months. Not because it's technically hard to include future months, it's trivially easy to write `=AVERAGE(B2:B13)`, but because including empty cells or placeholder zeros corrupts the signal. Your average reads low because the tool is counting months that contain no data as if they contain zero spending. That's not an accurate reflection of your habits. It's a mechanical artifact of a formula that has no concept of "this month hasn't happened yet."
This is exactly where an AI-native approach changes the conversation. Instead of forcing you to write conditional logic that checks today's date against each column header, a smarter system can understand intent: "average only the months where the month has ended." It can look at your data, recognize that January through March have real numbers while April is still in progress, and adjust the denominator automatically. No manual range updates. No fragile nested IF statements. The tool adapts to how you actually spend money, not to how you set up a grid.
What you've run into is the fundamental friction of legacy spreadsheets: they treat all cells as equal, but your data isn't equal. Some months are complete. Some are partial. Some haven't started. A budget tracker that can't distinguish between them isn't just annoying, it's misleading. The fix you're looking for isn't a better formula. It's a tool that understands time as a first-class concept, one that knows a month ends on its last day and that averages should only include what's already happened. That's the kind of intelligence that turns a spreadsheet into a partner, not a calculator you have to wrestle with every month.