Days Payable Outstanding (DPO)

How DPO is calculated

DPO = (Accounts Payable / Cost of Goods Sold or Total Purchases) × Number of Days in Period. For a service business that buys \$30,000/month of subcontractor services and software with \$45,000 in AP, monthly DPO is (45,000 / 30,000) × 30 = 45 days.

Like DSO, the metric can be biased by one large invoice that's about to be paid. Smoothing across a quarter gives a better signal than a single month's snapshot.

The trade-off

Stretching DPO is the cheapest form of working-capital financing — interest-free credit from suppliers. Walmart and Apple are famous for running 60-90 day DPOs. But for small service businesses, supplier relationships are direct and fragile: stretch a freelance subcontractor from 15 to 45 days and you may lose the relationship.

A defensible DPO is whatever your supplier explicitly grants you in writing. Beyond that, the gain from late payment is often offset by losing early-payment discounts (a 2/10 net 30 discount is roughly 36% annualized) and by losing priority on future deliverables.

How to extend DPO without burning suppliers

The cheapest way to extend DPO is to actually use the terms you already have. Many businesses pay invoices the moment they arrive, despite having net-30 or net-45 terms, simply because their AP process triggers on receipt rather than on due date. Implementing a weekly payment run that releases checks and ACH on the due date alone often adds 10-15 days to DPO with zero negotiation.

Negotiating longer terms is easier when volume is growing. Suppliers who want to keep your business will often move from net-30 to net-45 or net-60 in exchange for a multi-year commitment, an annual minimum, or a smaller monthly rebate. Frame the conversation around predictability of revenue rather than 'I need more time' — they want to lend you money less than you want a free loan.

There is a hard ethical and legal floor. Payroll, payroll tax, sales tax, and trust funds are not yours to stretch. Beyond that, deliberately paying a small supplier 90 days late to fund growth is a transfer of working capital from a smaller business to a larger one, and it tends to come back as worse pricing, lower-priority service, or eventually no service at all.

When DPO suddenly extends, ask why. A genuine policy change is fine — you renegotiated terms, you implemented a weekly payment run, you switched to AP automation. An accidental drift is a problem because it usually reflects either an AP backlog (operational) or deliberate cash conservation (financial). Either way, knowing the cause is what lets you decide whether the new DPO is sustainable.