Shopify Cash Flow Management: The 13-Week Forecast That Saves Brands
How to build a 13-week rolling cash forecast for a Shopify brand — including processor holdbacks, ad-spend pacing, inventory POs and refunds. Template logic inside.
Most Shopify brands that fail don't fail because they're unprofitable — they fail because they run out of cash three weeks before a big inventory order lands, or right after Q4 when refunds spike. A 13-week rolling cash forecast is the single highest-ROI artifact a fractional CFO builds.
Why 13 weeks (not 4, not 52)
Four weeks is too short — you can't see the next inventory PO coming. Twelve months is too long — assumptions decay fast in DTC. Thirteen weeks (one quarter) is the sweet spot: long enough to catch every major outflow, short enough that the forecast is actually accurate.
The inflows side
1. Forecasted net revenue by channel
Use trailing 8-week average per channel, adjusted for seasonality and ad-spend plan. Net of refunds (use trailing return rate, not zero).
2. Processor settlement timing
Shopify Payments: 2-day rolling deposit. Stripe: 2–7 days depending on risk profile. Klarna: 14–30 days. PayPal: holds 10–21% in reserve. Model each separately — the cash hits the bank later than the sale.
3. Other inflows
Wholesale invoices (factor in payment terms), affiliate income, financing advances, capital injections.
The outflows side (this is where brands underestimate)
4. Ad spend pacing
Daily, by platform. Meta and Google bill credit card — usually weekly. TikTok prepayment. Model the actual cash-out date, not the spend date.
5. Inventory POs
Largest single outflow most quarters. Model: 30% deposit on PO, 70% before shipment, plus duties/freight 4–6 weeks later. Always conservative on landing dates.
6. 3PL invoices
Pick/pack, storage, outbound shipping. Most 3PLs bill weekly Net-7 or Net-15. Use trailing 8-week average per unit × forecast volume.
7. Refunds and chargebacks
Hit cash 2–5 days after the refund is issued. Forecast using trailing refund rate × forecast revenue. Don't forget Q1 post-holiday spike (often 1.5–2x baseline).
8. Payroll, contractors, SaaS, rent
Mostly predictable. Watch for quarterly subscription renewals that surprise founders.
9. Tax: VAT, sales tax, income tax
VAT collected on EU sales is NOT your money — it leaves quarterly. Sales tax similar. Income tax quarterly. Most overlooked outflow category.
10. Debt service
Inventory financing repayments, bank line interest, credit card minimums.
The output that matters
Minimum cash balance over next 13 weeks · Week-by-week ending cash · Days until cash drops below 8-week operating buffer · Largest single outflow week
If your minimum balance dips below 8 weeks of operating cost, you have a problem. Below 4 weeks, you have an emergency. The forecast tells you 60–90 days in advance — enough time to delay a PO, slow ad spend, or pull a credit line.
The weekly cadence
- Monday morning: actual cash + last week's variance review
- Roll forecast forward one week
- Flag any week below buffer threshold
- Make one decision (PO timing, ad spend, financing draw) based on what you see
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