---
name: budget-builder-narrative
description: Structure a budget and write the narrative that explains and defends its assumptions. Use this skill whenever a user is building a budget, needs a budget narrative or justification, is planning next year's spend, or says 'help me build our budget', 'write the budget narrative', or 'justify these numbers'. Trigger whenever budget figures need structure and a written rationale that stakeholders will accept.
---

# Budget Builder and Narrative

## What this does and why it matters
A budget without a rationale is just a wish list that gets cut arbitrarily. This skill structures a budget and, crucially, writes the narrative that explains the assumptions behind each line, so the budget is defensible, understood, and more likely to survive review. The narrative is what turns numbers into a plan stakeholders buy into.

## Inputs to gather
1. The period and scope (whole company, department, project).
2. The revenue or funding assumptions.
3. The cost drivers and planned spend by category.
4. Prior actuals, for grounding.
5. The strategic priorities the budget should fund.

## Method

### 1. Anchor to priorities
A budget is strategy expressed in dollars. Tie spend to the priorities it funds, so reviewers see what each line buys, not just what it costs.

### 2. Make assumptions explicit
Every significant line rests on an assumption (headcount, growth rate, unit cost, timing). State them, because a budget is only as credible as its stated assumptions, and unstated ones invite suspicion.

### 3. Ground in history where possible
Compare to prior actuals and explain material changes, so the numbers feel evidence-based rather than pulled from air.

### 4. Build in reality
Flag where estimates are uncertain and where contingency is prudent, rather than presenting false precision.

### 5. Write the narrative per section
For each major category, a short rationale: what it funds, the key assumption, and why the amount. This is the defensible core.

## Output format
ALWAYS use:

# Budget: [Scope] | [Period]
## Overview (what this budget funds, top-line totals)
## Revenue / funding assumptions
## Expense plan by category (category | amount | vs prior | key assumption)
## Narrative by section (rationale for each major line)
## Key assumptions summary
## Contingency and areas of uncertainty

## Anti-patterns to avoid
- Numbers with no stated assumptions.
- No comparison to prior actuals.
- False precision that hides real uncertainty.
- Spend disconnected from any priority.

## Guardrails
This structures figures and assumptions the user provides; it is not financial advice. Never invent figures or assumptions; use placeholders for anything missing and flag it. The user is responsible for the accuracy of the underlying numbers.

## Example
A department budget ties each line to a priority, states the headcount and unit-cost assumptions behind the largest categories, compares to last year with explanations for the increases, and flags one uncertain vendor cost with a contingency.