Refactor — Tax-Bracket Calc with LET-Named Thresholds

A teammate's progressive-tax formula in column C works but is unreadable — five levels of nested IF, each repeating the same bracket numbers:

=IF(B2<=10000, B2*0.10, IF(B2<=30000, 1000+(B2-10000)*0.12, IF(B2<=60000, 3400+(B2-30000)*0.22, IF(B2<=100000, 10000+(B2-60000)*0.24, 19600+(B2-100000)*0.32))))

Five brackets (10%, 12%, 22%, 24%, 32%); the magic numbers 10000, 30000, 60000, 100000 are bracket ceilings. Your task is to refactor with LET so each ceiling is named once and B2 is bound to a single readable name.

Columns A–B contain TaxpayerID and Income for 10 taxpayers.

Your task:

1. In column C (TaxOwed), write a LET-bound version: bind taxableIncome to B2 and tier1Ceiling/tier2Ceiling/tier3Ceiling/tier4Ceiling to the bracket ceilings, then express the IF chain in terms of those names. (Names like t1 would visually shadow A1-style cell refs, so spell the role out.)
2. The cumulative-tax math at each bracket: 1000 + (taxableIncome − tier1Ceiling)*0.12 for bracket 2, 3400 + (taxableIncome − tier2Ceiling)*0.22 for bracket 3, 10000 + (taxableIncome − tier3Ceiling)*0.24 for bracket 4, 19600 + (taxableIncome − tier4Ceiling)*0.32 above bracket 4.
3. Drag-fill from C2 → C11.

Graded cells: C2 (T-001 5000 → 500), C7 (T-006 60000 → 10000), C11 (T-010 200000 → 51600).