Error handling in spreadsheets has long been a messy compromise between accuracy and practicality. The old habit of converting errors to the text string "NA" works, it keeps cells clean and FILTER functions happy, but it sacrifices precision. The smarter path is to embrace `NA()` as a true error value, because it signals intent rather than masking a problem.
Here is what this means in practice. When you use `NA()`, you are telling the spreadsheet, and anyone who reads it, that a missing value is deliberate, not an oversight. It triggers `ISERROR` and `IFERROR` exactly as intended, making your error handling logic more predictable. The common frustration with `FILTER` ignoring `NA()` cells is real, but the fix is straightforward: wrap your `FILTER` in `IFNA()` or use `FILTER` with a condition that excludes errors. That extra step is not busywork; it forces you to think about what your data should exclude, which leads to cleaner logic overall.
The user who posted this question noticed that AI tools consistently suggest `NA()` over text. That is not a quirk. It reflects a deeper truth about modern spreadsheet design: errors are not just problems to hide, they are signals to handle. Text strings like "NA" bypass that signaling. They look like data when they are not, and they can silently break downstream calculations that expect numeric or logical values. By using `NA()`, you align your workflow with how the spreadsheet engine actually works, rather than fighting it with workarounds.
So the practical takeaway is straightforward. Stop converting errors to text. Start using `NA()` for deliberate blanks, and build your formulas to handle errors where they occur. Yes, it means adding `IFNA` to your `FILTER` calls. Yes, it requires a shift in habit. But the result is a spreadsheet that communicates clearly, where a missing value is a known absence, not a disguised problem. That is the difference between a sheet that merely functions and one that you can trust.