# Thirteen Week Cash Forecast

> Projects weekly cash balance from actual inflows and outflows via a bundled calculator, flags the exact week the balance would breach a stated minimum, and sizes the shortfall, instead of a monthly cash view that's too coarse to catch a short but real liquidity gap. Use whenever the user needs near-term cash visibility, wants a rolling 13-week cash view, or has only a monthly cash forecast that's too coarse to catch a specific week where cash gets genuinely tight.

- Skill: `natan-mohart/thirteen-week-cash-forecast` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add natan-mohart/thirteen-week-cash-forecast`
- Raw SKILL.md: https://api.skillmd.com/api/skills/natan-mohart/thirteen-week-cash-forecast/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Natan-Mohart (https://skillmd.com/u/natan-mohart)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/natan-mohart/thirteen-week-cash-forecast

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# Thirteen-Week Cash Forecast

## When to use
Use whenever near-term cash visibility matters more than annual or monthly views — a business managing tight liquidity, preparing for a lender conversation, or simply wanting an early warning system for cash rather than finding out about a shortfall after it happens. A monthly cash view can show a comfortable average while hiding a specific week where the balance actually goes uncomfortably low.

## What it does
Projects the cash balance week by week from actual and projected inflows and outflows via a bundled calculator (the direct method, tracking real cash movements rather than deriving cash from an accrual P&L), and flags the exact week and dollar amount by which the balance would breach a stated minimum cash threshold, if any week does.

## Method
1. **Build inflows and outflows from real, specific sources** for each of the 13 weeks — actual collections expected (tied to the AR aging), actual payments scheduled (tied to AP aging and payroll dates), not a smoothed average of a monthly number divided by 4.3.
2. **Use the direct method**: track actual cash receipts and disbursements, not net income adjusted for non-cash items — the 13-week forecast's entire value is showing real cash timing, which an indirect, accrual-based method obscures.
3. **State the minimum cash balance the business needs to maintain** — whatever operational or covenant-driven floor actually matters, not zero.
4. **Run the bundled calculator** (`scripts/thirteen_week.py`) to get the week-by-week balance and an explicit flag for the first week (and every week) the balance would drop below that minimum.
5. **Treat a breach flag as needing a specific action before that week arrives**, not just an observation — draw on an available credit line, accelerate a specific receivable, delay a specific payable, or cut a specific planned outflow, named concretely rather than "we'll figure it out."
6. **Refresh the forecast weekly**, rolling the horizon forward, since a 13-week forecast built once and left untouched loses its main value, which is catching a problem with enough lead time to act.
7. **Compare this week's actuals against last week's forecast for the same week** as a standing accuracy check — a forecast that's consistently off in the same direction needs its underlying assumptions revisited, not just this week's numbers.

## Inputs
- Starting cash balance
- Weekly inflows and outflows for the 13-week horizon, built from real AR/AP timing and payroll dates
- The minimum cash balance the business needs to maintain
- Config saved as JSON matching the format documented at the top of `scripts/thirteen_week.py`

## Output format
Week-by-week table of inflows, outflows, net cash movement, ending balance, and headroom versus the minimum; explicit flag on the first breach week if any week's balance drops below the stated minimum, with the shortfall amount.

## Example
A monthly cash view shows the business comfortably cash-positive all quarter. The 13-week direct-method forecast reveals that in isolation, week 9 through week 13 show declining headroom as a large payroll and a vendor payment cluster in the same window while a major customer payment lands a week later than usual, though in this run the balance stays above the $200K minimum throughout, ending week 13 with $235,980, still $36K of headroom, a genuinely tight but not breaching result the monthly view alone would never have shown with this level of week-specific detail.

## Common pitfalls
- Building the forecast from a smoothed monthly average instead of real weekly inflow and outflow timing, hiding a specific tight week inside a comfortable average.
- Using the indirect, accrual-based method instead of tracking actual cash receipts and disbursements.
- Building the forecast once and not refreshing it weekly, losing the early-warning value that's the entire point of a 13-week view.