What makes D2C and ecommerce finance structurally different
Compared to SaaS or services businesses, UK ecommerce has four structural finance issues:
- Working capital is dominated by inventory. Cash gets locked into stock that may take 60-180 days to sell. The faster you grow, the more cash you lock up.
- Variable costs scale with revenue more than headcount does. COGS, shipping, payment processing, marketplace fees, returns — all move with units sold. A 30% revenue increase usually increases working capital by 30%+.
- Channel mix changes economics violently. Selling on Amazon at 15% take rate is a very different business to selling D2C at 30% blended CAC. Most operators don't have channel-level P&Ls.
- VAT and customs are genuinely complex post-Brexit. OSS/IOSS for EU sales, marketplace-collected VAT for Amazon, postponed VAT accounting on imports — every channel has different rules.
For broader UK ecommerce tax mechanics, see our sibling-site cluster on UK ecommerce accountancy at GoEcom.
The metrics ecommerce operators get wrong
Contribution margin per order (not gross margin)
Contribution margin = revenue − COGS − payment processing − shipping − returns. This is the number that matters, and Shopify's default "gross profit" doesn't include 3 of those 4. Most UK D2C founders quote gross margin in the 60-70% range but their true contribution margin is 25-40%. The CFO sets this up correctly inside the first 30 days.
Blended CAC vs paid CAC vs new-customer CAC
Three different numbers, often confused. Blended CAC divides all marketing spend by all new customers (including organic and repeat — which is why most agencies love quoting it; it looks great). Paid CAC divides paid spend by paid-acquired customers. New-customer CAC divides paid spend specifically into newly acquired customers (not repeat). The third one is what tells you if you can scale.
Cohort retention and LTV
D2C cohort retention is usually much weaker than founders assume — sub-15% repurchase at 12 months for many categories. A real LTV calculation by cohort, with a 24-36 month horizon, tells you what CAC you can realistically afford. Most operators are paying CACs that imply 5-year LTVs they will never achieve.
Days inventory outstanding (DIO)
Average days from cash going out (to a supplier or factory) to cash coming back (from a customer). Industry-typical: 80-150 days for D2C in physical product. Best-in-class with strong DTC and lean SKUs: 30-50 days. The CFO's job is to track this and squeeze it — it's where cash is hiding.
Inventory finance — the silent cash killer
The most common UK D2C failure pattern:
- Brand has a hit product, sells through in 8 weeks of last buy.
- Re-orders 3× the previous PO to "ride the wave" — £180k to a factory in Vietnam.
- 30% deposit at order (£54k cash out), 70% on shipment (£126k cash out 90 days later).
- Shipping + customs adds 30-45 days. Stock lands month 5.
- Sales hit a soft patch — instead of selling through in 8 weeks, takes 16. Cash comes back over months 5-9.
- In month 3-4, payroll, marketing, and rent still need paying. Founder runs out of cash with £180k locked in WIP/stock.
The fractional CFO fix: a proper inventory cash forecast that models PO commit dates, deposit timing, shipping ETAs, sell-through rates per SKU, and overlaps the financing. Plus one or more of: revenue-based financing (Wayflyer, Liberis, Uncapped), inventory finance (Capital on Tap, asset-backed lenders), or extending supplier terms (which often saves more than financing — many factories will move to 90 days if you ask).
Channel mix — D2C vs marketplace vs wholesale economics
A typical UK D2C operator at £3M annual revenue often has channel mix like:
| Channel | Revenue split | Gross margin | Effective contribution margin |
|---|---|---|---|
| D2C (Shopify) | 55% | 65% | 32% after CAC, shipping, returns |
| Amazon (FBA) | 25% | 62% | 28% after referral fee, FBA fees, PPC, returns |
| Wholesale | 15% | 42% | 38% after sales commissions, freight |
| Marketplace (Etsy, Faire) | 5% | 58% | 22% after platform fees, PPC, fulfilment |
Insight that usually shifts strategy: wholesale frequently delivers a higher contribution margin than Amazon, despite the headline gross-margin gap, because the per-unit acquisition cost is amortised across the wholesale buyer's whole order. Most operators have never run this analysis correctly — the CFO does it in week 2.
Marketplace VAT, OSS/IOSS and post-Brexit ecom tax
Brief tour of the VAT/tax landscape a UK ecommerce CFO needs to manage:
- OSS (One Stop Shop) — for B2C sales of goods INTO the EU above the €10k threshold. You register once in one EU country and file quarterly returns covering all EU B2C sales.
- IOSS (Import One Stop Shop) — for B2C imports INTO the EU below €150 per parcel. Charges EU VAT at point of sale rather than at customs.
- Amazon, Etsy, eBay marketplace-collected VAT — for sales below £135 (UK) or via certain structures, the marketplace becomes the VAT collector. Easy to mis-account on the seller's books.
- Postponed VAT Accounting (PVA) — UK importers can defer import VAT to the VAT return rather than paying at customs. Massive cash flow benefit; many operators don't have it switched on.
- Cross-border returns — the VAT treatment on a returned-and-refunded EU sale is fiddly. Get it wrong and you over-pay VAT.
The CFO doesn't usually do this filing themselves — your ecommerce accountant or specialist (which is where GoEcom matches you) handles the compliance — but the CFO needs to know the cash and margin impact and surface anomalies.
First 90 days for an ecommerce fractional CFO
| Week | Deliverable |
|---|---|
| 1-2 | Diagnostic — 13-week cash, last 12 months revenue by channel, contribution margin per order, current inventory balance and DIO |
| 3-4 | Cleanup of management accounts — proper allocation of platform fees, payment processing, returns, marketing spend |
| 5-6 | Contribution margin dashboard per channel (D2C, Amazon, wholesale, marketplaces) |
| 7-8 | Inventory cash forecast — PO commit dates, supplier terms, sell-through assumptions per SKU |
| 9-10 | CAC + LTV cohort analysis — true new-customer CAC by channel, 24-month cohort retention |
| 11-12 | 12-month forecast, working capital facility recommendation, hiring plan |
What UK D2C and ecommerce operators should pay
- £500k-£2M revenue: reporting tier, £750-£1,500/mo, 1-2 days/mo. Focus on getting contribution margin tracked correctly, basic cash forecast.
- £2M-£8M revenue: operating tier, £2,000-£5,000/mo, 2-5 days/mo. Add channel-level P&Ls, inventory cash modelling, CAC/LTV cohort analysis, working capital facility.
- £8M-£25M revenue: scale-up tier, £5,000-£9,000/mo, 5-9 days/mo. Add multi-entity if international, board cadence, M&A readiness, group structure planning.
Below £500k revenue, you need a Shopify-native bookkeeper, not a fractional CFO. Above £25M revenue or with PE behind you, full-time becomes appropriate.