What is zero-based budgeting (ZBB) and when is it most appropriate?
A core FP&A interview question — asked in analyst and associate interviews across IB, PE, and the Big 4.
THE SHORT ANSWER
Zero-based budgeting requires every expense to be justified from scratch each period, rather than using the prior year's budget as a baseline. It's most appropriate when a company needs to cut costs significantly, restructure, or shift strategy. ZBB forces managers to evaluate the cost-benefit of every activity, but it's time-consuming. I'd recommend it for discretionary costs like marketing or travel, but not for fixed costs like rent where ZBB adds little value.
WHAT INTERVIEWERS LISTEN FOR
- ✓Every expense justified from zero each period.
- ✓No automatic carryover from prior budget.
- ✓Best for cost reduction or strategic shifts.
- ✓Use for discretionary costs, not fixed costs.
COMMON MISTAKES
- ✗Thinking ZBB means starting from zero revenue.
- ✗Applying ZBB to all costs equally.
- ✗Ignoring the high administrative burden.
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