Nested IF formulas are incredibly common in corporate Excel — especially in HR and payroll. Whether you're building grading scales, bonus tiers, tax brackets, or eligibility rules, you always end up with the same structure: "if this, then that, otherwise if that, then this…"
The problem? Once you go beyond 3–4 conditions, the formula turns into a messy wall of brackets that's hard to read, debug, or share with colleagues. One wrong operator or misplaced bracket and the formula still works… it just gives the wrong answer.
IFS vs nested IF — why IFS is cleaner:
- You explain the business logic in normal words and Claude builds the IF or IFS formula correctly
- You paste a broken nested IF and Claude quickly finds the mistake — usually brackets or operators
- Claude decides whether to use IFS or nested IF based on your Excel version
- Claude adds a proper default case so the formula never returns unexpected results
IFS availability: IFS is available in Excel 365 and Excel 2019 or later. If you're on Excel 2016 or older, you need nested IF. Tell Claude which version you're using and it will choose the right approach automatically.
Six steps — from writing your logic as a plain list to a tested, production-ready formula.
Write the logic as a simple list first
Before opening Claude, list your conditions clearly — 90 or above → A, 80 or above → B, and so on. This list becomes your prompt. The clearer the list, the better the formula.
Tell Claude your Excel version
IFS is much nicer, but only works in Excel 365 and 2019+. Mention your version so Claude picks the right method — IFS if available, nested IF if not.
Specify the cell to test
Tell Claude exactly which cell contains the value being tested — for example "the score is in B2". This way the formula is ready to paste directly into your sheet.
Read the explanation, not just the formula
Claude explains each condition in plain English alongside the formula. Read it. This is the best way to catch a logic error — like a > that should be >= — before it spreads across your data.
Test at the exact boundary values
Always test with the cutoff values themselves — 90, 80, 70, 69. Boundary cases are where IF formulas most often fail because of > vs >=. One character makes the difference.
Add a safety net for unexpected values
Make sure the formula handles edge cases — empty cells, text in a number column, values outside the expected range. Claude can add a final TRUE, "—" default case or an IFERROR wrapper to catch these cleanly.
B2>=90 before B2>=80. Claude handles this automatically, but it's worth understanding why.Copy these prompts into Claude. Replace the bracketed placeholders with your actual logic and cell references.
Build from scratch prompt
Debug prompt
Payroll bonus prompt
TRUE, "—" as the final pair. Without it, IFS returns an error if nothing matches.