Ecommerce has a cash flow shape that catches out even fast-growing, profitable brands. You pay for stock upfront, often months before it arrives. You pay for the advertising that sells it before a single order comes in. And when the orders do land, the money does not reach your bank the moment a customer clicks “buy” – the marketplace or payment processor holds it first. The faster you grow, the wider that gap gets. It is entirely possible to double your sales and run out of cash in the same quarter.
This guide is about the working capital mechanics that are specific to selling online: marketplace payout lags, advertising spend as a cash drain, imported-stock lead times, and returns. If you run a physical shop as well, our guide to working capital for UK retailers covers the till-and-shelf version of the problem. Online-only sellers face a different and usually harsher cash cycle, and that is what we deal with here.
Why Selling Online Ties Up Cash Differently
A high-street shop takes cash or card at the till and has the money within a day or two. Its working capital problem is mostly stock on the shelves. An online business inverts several of those advantages at once.
First, you rarely hold a few days of stock. To keep listings live and shipping fast, most ecommerce brands carry weeks or months of inventory – and if they import it, they pay for it long before it lands. Second, you do not get paid instantly. Whether you sell through Amazon, your own Shopify store or both, your takings sit in a processor or marketplace account and are released on a schedule you do not control. Third, you spend heavily on customer acquisition before the sale, not after. Put together, an online brand can have its cash tied up in stock in a container, in a marketplace reserve, and in last week’s ad spend all at the same time.
That is why so many ecommerce founders are profitable on paper but permanently short of cash. The profit is real; it is just locked up in inventory and pending payouts while the bills for the next batch of stock and the next month of ads are already due.
The Ecommerce Cash Conversion Cycle
The clearest way to see the squeeze is through the cash conversion cycle – how long a pound is tied up between paying for stock and getting paid by the customer. Here is roughly how the numbers look for a UK online seller.
| Metric | Typical benchmark | What it means |
|---|---|---|
| Days Inventory Outstanding (DIO) | 60–120 days | Higher for imported goods; you fund stock long before it sells |
| Days Sales Outstanding (DSO) | 3–27 days | Not customer credit – it is the marketplace or processor payout lag |
| Days Payable Outstanding (DPO) | 0–30 days | Overseas suppliers often want deposits upfront, so DPO is low |
| Cash Conversion Cycle (CCC) | +40 to +110 days | Strongly positive – cash is locked up for months at a time |
Compare that with hospitality, where the cycle is negative because customers pay instantly and suppliers give credit. Ecommerce is the opposite: a long, positive cycle where you fund everything first. The DPO figure is the killer. A traditional shop buying from UK wholesalers on 30 or 60 days uses its suppliers as free finance. An online brand importing from overseas usually pays a deposit before production even starts, so it gets almost no supplier credit at all – the DPO that would normally shorten the cycle simply is not there.
The Marketplace Payout Lag Is Your Real DSO
Online sellers do not offer customers credit, so you might assume your DSO is zero. It is not. Your cash is held by whoever processes the payment, and in 2026 those hold periods have grown.
On Amazon, the disbursement cycle is roughly every 14 days, and since 12 March 2026 the Delivery Date Based Reserve (DD+7) policy holds funds until seven days after an order is confirmed delivered. In practice, an FBA seller now waits somewhere between 14 and 27 days from a sale to the money reaching their bank, and a rolling account-level reserve sits on top to cover potential returns and claims. If your whole business runs through Amazon, you are effectively financing two to four weeks of sales at all times – and that reserve grows exactly when you grow.
On your own Shopify store, Shopify Payments settles in about three business days in the UK, plus a day or two for your bank. Faster than Amazon, but weekends do not count, and newer stores start on a longer settlement period that only shortens once you have a reliable fulfilment record. Sell through PayPal, Klarna or other providers and each has its own timetable and occasional holds. The practical point is that “instant” online sales are nothing of the sort, and the busier your weekend, the more cash is in transit rather than in your account.
Know your real position: use our free working capital calculator to work out how many weeks of cover you have once stock, ad spend and pending payouts are accounted for – not just what the bank balance says today.
Advertising Spend Is Working Capital, Not Just a Cost
The line most ecommerce owners misread is marketing. In an online business, paid advertising on Meta, Google or TikTok is not merely an expense – it behaves like inventory. You pay it upfront, and it converts into cash slowly as those customers buy, come back and, if you are lucky, tell their friends.
The gap matters because your customer acquisition cost is paid today while the revenue arrives over days, weeks or, for subscription and repeat-purchase brands, months. If your payback period on ad spend is 45 days but your stock and ads both need paying now, every pound of growth pulls cash out of the business before it brings any back. This is the mechanism behind overtrading – scaling ad spend faster than the cash cycle can support, until a profitable business simply runs dry. The more efficient your advertising looks on a spreadsheet, the more tempting it is to pour cash into it, and the faster the trap closes.
Importing Stock: The 90-Day Cash Gap Before Goods Even Land
For brands importing from China or elsewhere in Asia, the single biggest chunk of trapped cash sits in the supply chain. A typical order runs like this: pay a 30 per cent deposit to start production, wait four to eight weeks for manufacture, pay the 70 per cent balance before the goods ship, then wait four to six weeks for sea freight, customs and delivery to your warehouse. From the first deposit to a saleable pound of stock can easily be 90 to 120 days – and you have paid for all of it before you sell a single unit.
Two things make this worse in 2026. Currency is one: paying suppliers in dollars means an adverse move between order and payment quietly raises your landed cost. The other is that you cannot reorder little and often the way a UK-supplied shop can, so you commit large sums to each shipment and carry more safety stock to cover the lead time. That inflates days inventory outstanding and is precisely why an importing brand’s cash conversion cycle runs so long. If your suppliers are overseas, mapping this timeline is the most important cash-flow exercise you will do.
Returns Quietly Drain the Model
Returns are a working capital event that physical retailers barely notice and online sellers cannot ignore. UK ecommerce return rates commonly run at 20 to 30 per cent in categories like fashion and footwear, and every return reverses a sale you have already banked, may have already spent, and now have to refund – while the stock comes back as used, delayed or unsaleable.
Marketplaces build this into their reserves, which is part of why Amazon holds a rolling buffer against your balance. On your own store, the cash simply leaves when you refund. If you plan your reorders and ad spend off gross sales rather than sales net of returns, you will consistently overcommit cash. Model your numbers on what you actually keep.
Two UK Ecommerce Examples
Jade runs a homeware brand selling through Amazon FBA from Nottingham, turning over about £900,000 a year. On paper she makes a healthy 18 per cent net margin. In practice she is permanently overdrawn. The reason is the stack of simultaneous cash claims: roughly £70,000 of stock sitting in Amazon’s warehouses, another £25,000 held in her Amazon balance under the 14-day cycle and the DD+7 reserve, and £12,000 of ad spend she paid this month to drive next month’s orders. When a container of new stock needed a £40,000 balance payment in the same fortnight as her VAT bill, her profitable business could not find the cash. Nothing was wrong with the margins – the money was real, but every pound of it was tied up somewhere she could not reach. Her fix was to build a rolling forecast that tracked cash by the week, not the month, and to stagger reorders so a stock payment and the VAT quarter never collided again.
Marcus and Priya run a DTC skincare brand from Bristol on Shopify, importing components from Asia, with revenue of £1.4 million. Their cash conversion cycle is close to 100 days: 90-odd days from supplier deposit to saleable stock, three business days for Shopify to settle, and almost no supplier credit because manufacturers want deposits upfront. Growth made it worse rather than better – each 20 per cent jump in sales meant a bigger container order, paid months ahead, plus more ad spend to fill it. They were expanding and getting poorer at the same time. They broke the cycle two ways: negotiating 30-day terms with their UK packaging and fulfilment suppliers to claw back some DPO, and putting an inventory and revenue-based finance facility in place to bridge the container-to-cash gap, so a big reorder no longer meant an empty bank account.
Funding the Gap Without Stalling Growth
Because the ecommerce cycle is long and positive, most growing brands need some form of finance to bridge it – the alternative is capping growth at whatever your own cash can fund, which for a scaling brand is painfully low. The relevant options are different from the invoice-based products a trade business would use, because you have no unpaid invoices to borrow against.
The main routes are inventory finance and trade finance, which fund the stock purchase itself; revenue-based finance and merchant cash advances, where repayments flex with your sales; and marketplace-specific lending such as Amazon Lending or the funding built into platforms like Shopify Capital. Each has a place, and each has a cost that eats margin, so the discipline is to use finance to fund the predictable cycle – the container you know you will sell – rather than to paper over a business that is simply spending more than it earns. Our guide to working capital finance options for UK SMEs compares these in detail. If your sales are heavily seasonal, with a Q4 peak that has to be bought months ahead, read it alongside our guide to funding a seasonal peak.
What To Do Next
Start by calculating your real cash conversion cycle. Add up the days your money is tied up in stock (from supplier deposit to sale, not just from arrival), add the payout lag from every channel you sell through, and subtract whatever supplier credit you genuinely get. If the answer is 60 days or more – and for most importing brands it is – that is the number of days of trading you have to fund out of your own pocket before finance.
Then build a 13-week cash flow forecast with weekly rows, because monthly forecasts hide the whole problem: the container balance, the VAT quarter, the ad spend and the marketplace payout all land on different weeks. Plan reorders and advertising off sales net of returns, not gross. Stagger big stock payments so they never collide with VAT or a wage run. And before you scale ad spend, know your payback period – if it is longer than your cash can bridge, faster growth will make you poorer, not richer. If the profit looks fine but the bank never does, our guide on being profitable but always short of cash shows exactly where an online brand’s money goes.