Working Capital Optimisation: Practical Levers for High-Growth Businesses

The Working Capital Trap

Working capital management is one of the most neglected disciplines in early-stage companies. Founders focus on revenue growth, product development, and fundraising. Cash flow management gets attention when there is a crisis. But for businesses that sell on credit, carry inventory, or pay suppliers faster than they collect from customers, working capital dynamics can be the difference between a business that survives rapid growth and one that does not.

The fundamental principle is straightforward: working capital is the cash tied up in the operating cycle of the business. The longer the cycle and the faster the business is growing, the more cash is needed to fund that cycle. A business growing at 100% per year needs roughly twice as much working capital at the end of the year as it did at the start. If that cash is not available, growth stalls.

The Cash Conversion Cycle

The cash conversion cycle (CCC) is the standard measure of working capital efficiency. It measures the number of days between paying for inputs and receiving payment from customers:

CCC = Days Inventory Outstanding (DIO) + Days Sales Outstanding (DSO) - Days Payables Outstanding (DPO)

Each component measures a different part of the operating cycle:

• DIO (Days Inventory Outstanding): the average number of days inventory is held before being sold. For a SaaS business, this may be zero. For a business with physical products (including those with embedded finance components requiring physical card issuance), this can be significant.
• DSO (Days Sales Outstanding): the average number of days between invoicing a customer and receiving payment. For B2B businesses billing on 30-day terms but experiencing average payment at 45-50 days, the DSO is typically 45-50, not 30.
• DPO (Days Payables Outstanding): the average number of days between receiving a supplier invoice and paying it. A longer DPO reduces the working capital requirement; it essentially uses supplier credit to fund the operating cycle.

A shorter CCC means the business needs less cash to fund the same level of revenue. A longer CCC means more cash is tied up per pound of revenue. The relationship is direct: if the CCC is 30 days and daily revenue is £10,000, approximately £300,000 of cash is tied up in the operating cycle at any given time.

Levers on the Receivables Side

Reducing DSO is the most impactful single working capital lever for most B2B businesses. The tools available are:

Invoice Terms and Billing Timing

Many companies inadvertently extend their DSO by billing inefficiently. Raising invoices at month-end rather than immediately on delivery, using 30-day terms when the market would accept 14-day terms, or sending invoices by post rather than electronically all extend the effective payment cycle without any strategic intent. An audit of the actual invoicing process, from delivery to invoice issuance, often reveals 5-10 days of avoidable DSO.

Early Payment Incentives

Offering a small discount for early payment (typically 1-2% for payment within 10 days) is an effective way to accelerate collections from customers who have the cash available. The cost of the discount must be compared against the cost of the working capital it releases; at current bank rates, a 1% discount for 20-day early payment represents an annualised cost of approximately 18%, which is higher than most businesses would pay for an overdraft. Early payment discounts are most useful when the alternative is invoice financing rather than a cheap credit facility.

Invoice Financing

Invoice financing (also known as invoice discounting or factoring) allows a business to access cash against outstanding invoices before the customer pays. The lender advances typically 85-90% of the invoice value immediately, with the balance (less fees) paid when the customer settles. The cost is typically 1.5-3.5% per month of the finance drawn, which represents a significant annualised cost but can be rational for businesses with large receivables books and limited access to other credit facilities.

Levers on the Payables Side

Extending DPO without damaging supplier relationships requires careful management. The tools available are:

Supplier Payment Terms Negotiation

For businesses that have reached a meaningful scale and are good customers for their key suppliers, negotiating extended payment terms (from 30 days to 45 or 60 days) is a low-cost way to reduce working capital requirements. Suppliers are often willing to extend terms for reliable customers, particularly if the alternative is losing the business entirely. The value of 15 additional days of payables for a business spending £5m per year with a supplier is approximately £200,000 of cash that is permanently available at no cost.

Supply Chain Finance

Supply chain finance (also known as reverse factoring) allows a business to offer its suppliers early payment on its invoices, funded by a bank or finance provider, at the buyer's credit rate rather than the supplier's. The buyer pays the bank on extended terms. This is most relevant for larger businesses with investment-grade or near-investment-grade credit ratings; for early-stage companies, the economics are less favourable.

How Growth Destroys Working Capital: The Growth Cash Trap

The growth cash trap is a specific and particularly dangerous working capital dynamic that affects fast-growing businesses. It works as follows: as revenue grows, the stock of outstanding receivables, inventory (where applicable), and prepaid costs grows proportionally. This increase in working capital must be funded from somewhere. If the business is not generating sufficient cash from operations to self-fund this increase, it must be funded from the balance sheet (existing cash reserves) or through additional financing.

A worked calculation illustrates the scale of the problem. Consider a business with annual revenue of £3m, a 30-day DSO, and a 30-day DPO with no inventory. Its working capital requirement is approximately £250,000 (one month of net revenue). If the business grows to £6m revenue in the following year, its working capital requirement doubles to approximately £500,000. The business has consumed £250,000 of cash funding that operating expansion, even if it is profitable throughout the period. A business growing at 100% per year with a 60-day CCC and £6m revenue is consuming approximately £500,000 of cash per year in working capital alone, separate from any operating losses.

Financing the Working Capital Cycle

The options for financing the working capital cycle in a high-growth business are:

Key Takeaways

• The cash conversion cycle (CCC = DIO + DSO - DPO) measures how many days of revenue are locked in the operating cycle. Every day of improvement in CCC releases cash.
• Growth destroys working capital: a business growing at 100% doubles its working capital requirement in a year. This must be funded or growth will be cash-constrained even if the P&L is profitable.
• The most impactful receivables lever is reducing DSO through faster invoicing and more rigorous collections. UK SME average DSO is 47 days against 30-day terms; the gap represents recoverable cash.
• Extending supplier payment terms is a zero-cost working capital lever for businesses with strong supplier relationships and reliable payment history.
• Invoice financing and revolving credit facilities are the primary debt-based tools for funding working capital growth. The right choice depends on the business's credit profile and the cost of the facility relative to the equity alternative.
• Financial models must include a working capital section that calculates the cash required to fund the operating cycle at each stage of the growth plan. Omitting this is one of the most common modelling errors.