How to Find a Tax Bracket with LOOKUP in Excel

Find each salary’s marginal rate in a bracket table with LOOKUP, then calculate the full progressive tax.

You will learn to

• Use LOOKUP’s vector form on a sorted bracket table
• Use the array form, which returns from the last column
• Calculate progressive tax from base tax plus the marginal slice

How it works

LOOKUP(lookup_value, lookup_vector, result_vector) always does an approximate match: it finds the largest value in a sorted lookup_vector that is less than or equal to the lookup value and returns the item in the same position of result_vector. That is exactly how tax brackets work, so =LOOKUP(B2,E2:E6,F2:F6) returns the marginal rate for the income in B2.

To calculate the tax itself, store the tax due at the start of each bracket, then add the rate on the slice above the threshold: base + (income − threshold) × rate. The bracket table must be sorted from the lowest threshold up.

=LOOKUP(B2,E2:E6,F2:F6)