Inventory Buying Plans: Funding Stock Without Killing Cash
A virtual CFO's method for an inventory buying plan: open-to-buy discipline, reorder maths, weeks-of-cover targets, and protecting cash through…
Every product business learns the same lesson eventually, usually the hard way: the profit is real, but it is sitting in the warehouse, and the business is short of cash right when it should be strongest. An inventory buying plan is the discipline that stops that happening. It is a cash document before it is a stock document, and its job is to buy enough to sell without tying up more cash than the business can spare. This is a virtual CFO’s method for building one.
Published: July 2026
Founders tend to think of a buying plan as an operational tool, how much stock to order and when. It is that, but its more important role is financial: it is the plan for how much cash the business will have tied up in inventory at each point in the year. Every buying decision is a cash decision, because a dollar committed to stock is a dollar unavailable for anything else until that stock sells.
Treating the buying plan as a cash document changes how it is built. Instead of starting from what you want to sell and ordering to match, you start from how much cash you can afford to have locked in stock, and you buy within that constraint. The plan becomes the bridge between the sales ambition and the cash reality, which is exactly where product businesses get into trouble when they have no plan at all. It is the operational companion to the self-funded growth rate and a natural 90-Day Number build for a product business.
The core discipline of a buying plan is open-to-buy: the amount of new stock you can commit to for a period, given what you plan to sell, the cover you want to hold, and what you have already ordered. The logic is simple. Take your planned sales for the period, add the stock cover you want to end the period with, subtract the stock you already have and the orders already committed, and what remains is your open-to-buy: the budget available for new purchasing.
The value of open-to-buy is that it imposes a ceiling. Without it, buying is driven by supplier minimums, enthusiasm for a new range, or fear of stockouts, and it routinely overshoots what the business can fund. With it, every buying decision is checked against a budget that reflects both the sales plan and the cash constraint. It turns “order more of everything that is selling” into “order within what we can afford to hold”, which is the discipline that keeps cash from vanishing into stock.
Alongside the budget sits the reorder mechanics: when to reorder each product so it neither stocks out nor overstocks. The reorder point is the stock level at which you place a new order, and it is built from two things: the demand over the supplier’s lead time, plus a safety buffer for variability.
Worked simply: if a product sells 10 units a week and the supplier takes 6 weeks to deliver, lead-time demand is 60 units. Add a safety stock to cover demand running hotter than expected or the supplier running late, say another 20 units, and the reorder point is 80 units. When stock falls to 80, you reorder. Set the reorder point too low and you stock out during the lead time, losing sales; set it too high and you carry excess cash in stock. The maths is not complicated, but doing it per product, rather than reordering on gut feel, is what keeps both stockouts and overstock under control.
Not every product deserves the same amount of stock. Weeks of cover, the number of weeks of sales your current stock represents, should vary by SKU class. Your core, fast-moving, reliably selling products can carry more cover safely, because they will sell through. Slow-moving, uncertain, or seasonal products should carry less, because cover on a product that may not sell is just trapped cash. Setting a target weeks-of-cover by class, more for the champions, less for the tail, is how you allocate your inventory cash to where it works hardest. This connects directly to SKU profitability, where the tail’s excess cover is often the first cash to free.
The sharpest cash test for a product business is the pre-buy before a peak season. To have stock on the shelf for the peak, you must buy and pay for it weeks or months ahead, which opens a cash trough: cash goes out for stock well before the sales come in. A business that does not plan this can find itself unable to fund the very inventory that drives its best quarter, or forced to under-buy and miss the peak.
The buying plan’s job here is to quantify the trough and set it against the cash position, so the founder can see how deep it goes and when, and arrange to fund it deliberately. This is where the buying plan meets the 13-week cashflow forecast: the pre-buy shows up as the largest cash outflow of the cycle, and seeing it coming is the difference between funding it calmly and scrambling. Supplier terms become a real lever here, because every week of payment terms is a week the supplier funds the stock instead of you.
Take a $6M DTC brand heading into Q4, its biggest quarter. To stock the peak it must pre-buy in September and October, committing, say, $900,000 of stock purchases, paid on terms that fall largely before the Q4 sales arrive. The buying plan models the trough: cash dips sharply through October as the stock is paid for, reaching a low point in early November before the Q4 revenue starts landing and refilling it. Knowing the trough is roughly $900,000 deep and bottoms in early November, the founder can arrange the funding in August, when it is cheap and calm to do so, rather than discovering the gap in October. Negotiating an extra 30 days of supplier terms on part of the buy shifts a meaningful slice of that funding onto the supplier, shrinking the trough further. The plan turns a potential crisis into a scheduled, funded event.
Why is an inventory buying plan a cash document?
Because every buying decision commits cash: a dollar in stock is a dollar unavailable until that stock sells. The plan’s most important job is managing how much cash is tied up in inventory across the year, not just how much stock to order. Building it from the cash you can afford to lock up, rather than from sales ambition alone, is what keeps a product business solvent through growth.
What is open-to-buy?
Open-to-buy is the budget available for new stock purchases in a period: planned sales, plus the cover you want to end with, less stock on hand and orders already committed. It imposes a ceiling on buying, so purchasing is checked against both the sales plan and the cash constraint rather than driven by supplier minimums or fear of stockouts.
How do I set a reorder point?
Take demand over the supplier’s lead time and add a safety buffer. If a product sells 10 units a week and the supplier takes 6 weeks, lead-time demand is 60 units; add, say, 20 units of safety stock and reorder at 80. Doing this per product, rather than on gut feel, keeps you from both stocking out during the lead time and carrying excess cash in stock.
How much stock cover should I hold?
It varies by SKU class. Fast-moving, reliable products can carry more weeks of cover because they will sell through; slow, uncertain, or seasonal products should carry less, because cover on stock that may not sell is trapped cash. Setting target weeks-of-cover by class allocates your inventory cash to where it works hardest.
How do I fund a peak-season stock build?
By modelling the cash trough the pre-buy creates, how deep and when, against your cash position, and arranging funding in advance. The pre-buy is usually the largest cash outflow of the year, landing before the peak revenue. Seeing it coming lets you fund it calmly, and negotiating extra supplier payment terms shifts part of the funding onto the supplier, shrinking the trough.
Should I use inventory finance?
Financing the trough can be sensible, but it is a decision to make deliberately against the modelled gap, not a default. The buying plan quantifies exactly how much you need and for how long, which lets you compare the cost of a facility against the margin it protects and against the cheaper lever of supplier terms. This guide does not recommend specific financiers; it frames the decision.
Can a virtual CFO build my buying plan?
Yes. An inventory buying plan tied to your cashflow is a defined deliverable and a natural 90-Day Number for a product business. The output is a model you own, with open-to-buy discipline, reorder points, weeks-of-cover targets, and the peak-season trough quantified against your cash, so you can run your buying without killing your cash.
Sydney Virtual CFO is a Sydney-based virtual CFO service for founders running $2M to $15M businesses across SaaS, ecommerce, professional services, construction, and other low-volume, high-value industries. We deliver fixed-scope CFO engagements with a named deliverable on day 90: a 13-week cashflow forecast, a fundraise-ready financial model, a unit economics build, or a board reporting pack you can run on your own.
Our front-door product, the 90-Day Number, is fixed scope at $17,850 plus GST. We are one of the few project-based virtual CFOs in Australia, in a market built almost entirely on monthly retainers. No retainers without a deliverable. No 80-page reports. No theatre.
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This content is general information only, written for Australian founders running businesses in the $2M to $15M revenue range. It does not constitute tax, financial product, investment, or legal advice and should not be relied on as such. The work referenced is led by a Chartered Accountant (CA ANZ), but Sydney Virtual CFO is not a licensed tax agent, not a licensed financial adviser, and not authorised to provide personal financial advice. Tax obligations, accounting treatments, fundraise terms, and statutory requirements depend on your individual circumstances. For advice specific to your business, contact the team directly or consult a registered tax agent, licensed financial adviser, or qualified lawyer. Information was current at the time of publication and may change without notice. We review and update guides periodically.
