Two philosophies, one budget
Top-down budgeting starts with a target -- usually set by the board or executive team -- and allocates it downward across departments and cost centres. Bottom-up budgeting starts with individual department plans and rolls them up into a company total.
Neither approach works perfectly in isolation. Top-down budgets often bear little resemblance to operational reality. Bottom-up budgets frequently exceed what the business can afford. The art of budgeting lies in combining them.
How top-down works in practice
The board sets strategic targets: revenue growth of 25%, EBITDA margin of 15%, headcount growth capped at 20 new hires. Finance translates these into departmental envelopes. Each department receives a spending ceiling and plans within it.
Strengths: Fast, aligned with strategic goals, ensures the total budget is affordable.
Weaknesses: Departments feel constrained by arbitrary targets. The budget may require operational changes that are not feasible within the timeline. Engagement from budget owners is low because they did not build the numbers.
How bottom-up works in practice
Each department builds a detailed plan based on their operational needs: specific hires, project costs, vendor contracts, and programme budgets. Finance consolidates these into a company-level P&L.
Strengths: Accurate at the operational level, high ownership from budget holders, reflects genuine business needs.
Weaknesses: Slow to produce, nearly always exceeds the affordable total, requires multiple rounds of negotiation to bring into line.
The hybrid approach
The most effective budgeting processes use both methods in sequence:
Step 1: Top-down target setting. Leadership defines the high-level financial framework: revenue targets, margin goals, and total headcount. These set the boundaries.
Step 2: Bottom-up building within guardrails. Departments build their detailed plans, but within the envelope set by step one. If engineering's bottom-up plan exceeds their allocation, they must prioritise -- not simply submit and hope for the best.
Step 3: Gap analysis and negotiation. Finance identifies where bottom-up plans diverge from top-down targets. These gaps become the agenda for budget review meetings. Some gaps result in target adjustments; others result in operational changes.
Step 4: Final reconciliation. The approved budget reflects both strategic intent and operational reality. Every department has a plan they helped build within boundaries they understand.
Making the hybrid work
The key enabler is transparency. When departments can see the total budget envelope and understand why their allocation is what it is, the negotiation becomes constructive rather than adversarial.
A planning platform that shows real-time rollups as departments submit their plans makes this transparency effortless. Finance can watch the bottom-up total converge toward the top-down target and intervene early when gaps appear.