An open 30-day account, usually called Net 30, is a short-term trade credit arrangement in which a seller ships goods or delivers services now and the buyer pays the full invoice within 30 calendar days. It’s the default payment structure in most business-to-business relationships, and it exists to bridge the gap between when a business receives inventory and when it earns the revenue to pay for that inventory. No interest accrues during those 30 days, and there is no minimum payment — the entire balance comes due at once.
How the 30-Day Clock Starts
The countdown runs from the invoice date, which is usually the day goods ship or the day a service is completed. Shipping terms in the purchase agreement can shift that date. Under FOB Shipping Point, the buyer takes ownership when goods leave the seller’s dock, and the invoice date typically aligns with the ship date. Under FOB Destination, the seller keeps ownership until goods arrive, which can push the effective invoice date later. If your contract is silent on the point, ask before the first order goes out. A few extra days of float matter when you’re managing cash across a stack of vendor accounts.
Net 30 is the standard assumption unless the invoice or credit agreement explicitly states otherwise. Some industries operate on Net 60 or Net 90, but 30 days is the default starting point for most trade relationships.
Early Payment Discounts and When They’re Worth It
Sellers often offer a discount for paying before day 30. The most common form is written as “2/10 Net 30,” meaning you can deduct 2% from the invoice by paying within 10 days instead of 30.
On a $10,000 invoice, that saves $200 for paying 20 days early. Annualized, that small percentage works out to roughly 36.7%. The math: divide the discount by the net amount (2 ÷ 98 ≈ 2.04%), then multiply by the number of 20-day periods in a year (360 ÷ 20 = 18). 2.04% × 18 ≈ 36.7%. That return dwarfs what idle cash earns in most business accounts, which is why taking the discount is almost always the right move if you can cover the early payment.
Terms vary. You may see “1/10 Net 30” or, on some high-margin goods, “5/10 Net 30.” The logic is the same in every case: compare the annualized return on paying early against your cost of borrowing. Even if you’d need to draw on a 10% line of credit to fund the early payment, a 36.7% effective return still leaves you well ahead.
What Happens If You Pay Late
Missing the deadline triggers consequences that stack quickly. Most sellers charge a late fee calculated as a monthly percentage of the outstanding balance, commonly 1% to 2%. That’s 12% to 24% on an annual basis, expensive money by any standard. State usury laws cap what sellers can charge on overdue invoices, but the caps vary widely.
The fee is often the least painful part. On day 31 the seller can suspend your open account and force every future order onto cash on delivery. For a business that depends on the supplier for inventory or raw materials, losing credit terms disrupts operations far more than the penalty itself. Your team suddenly needs cash in hand before anything ships.
Persistent late payments lead to permanent account closure and referral to a collections agency. At that point the damage spreads outward. Other vendors checking your business credit history will see the delinquency and may tighten their own terms or decline to extend credit at all.
How to Get Approved
Opening a Net 30 account starts with a credit application submitted to the seller. It typically asks for your business entity details, financial statements, bank references, and trade references — contact information for other suppliers who already extend credit to you. The seller contacts those references to verify your outstanding balances and payment patterns.
Based on that credit investigation, the seller sets an initial credit limit: the maximum dollar amount of unpaid invoices you can have outstanding at any one time. A $50,000 limit does not mean $50,000 per month. It means the total of all your open invoices can never exceed that threshold. If you have $45,000 in unpaid invoices and want to place a $10,000 order, you’ll need to pay down at least $5,000 first.
Limits are reviewed periodically, often annually. Buyers who consistently pay within terms or take early payment discounts are strong candidates for increases. A pattern of payments arriving after day 30 will likely prevent any increase and can trigger a reduction. The track record you build with each vendor is a rolling audition for better terms.
Watch for a Personal Guarantee
Some sellers, particularly those dealing with newer or smaller businesses, require a personal guarantee from the owner as a condition of opening the account. A personal guarantee lets the seller pursue the owner individually if the business can’t pay, effectively bypassing the liability protection of a corporation or LLC. Read the credit agreement carefully before signing. That single clause can put your personal assets on the line for what looks like a routine vendor relationship.
How Net 30 Differs From a Credit Card
A Net 30 account and a revolving credit card serve different purposes, and the mechanics reflect that. The most important distinction is the payment structure. A Net 30 account demands full payment by the due date. There is no minimum payment, and you cannot carry a balance into the next cycle. A credit card lets you pay a fraction and roll the rest forward, charging interest on whatever remains.
The cost of falling behind works differently too. A late Net 30 payment triggers a flat monthly fee on the overdue amount. A credit card charges compound interest on the unpaid balance based on the card’s APR, and that interest accrues daily. Credit cards offer a grace period on new purchases when the previous statement is paid in full. Trade credit offers no equivalent. The 30-day window is the entire interest-free period.
The reporting systems are also separate. Net 30 accounts feed your business credit profile. Credit cards affect your personal FICO score. The two ecosystems rarely overlap unless a personal guarantee is involved.
Impact on Your Business Credit
Open 30-day accounts feed into your business credit profile, tracked by commercial credit bureaus like Dun & Bradstreet rather than the consumer bureaus behind your personal FICO score. D&B assigns a Paydex Score from 1 to 100 that reflects how promptly your business pays its bills. A score of 80 means payments have generally been made within terms.1Dun & Bradstreet. Paydex Score Factsheet Scores in the 50–79 range indicate moderate payment risk, and anything below 50 signals high risk of late or missed payments.
A strong Paydex matters more than many owners realize. Other vendors check it before extending credit. Lenders and insurers reference it when evaluating your business. A weak score restricts your ability to get favorable terms across the board, and the higher cost of doing business tends to make cash flow worse.
Paying early pushes your Paydex above 80, which makes your business especially attractive to new suppliers. The score is weighted toward recent payment history, so a business recovering from past problems can rebuild relatively quickly with 12 months of disciplined payments.
One crossover worth knowing: if the account was opened with a personal guarantee and the debt eventually goes to a collections agency, that negative item can land on your personal consumer credit report. A business obligation can end up affecting your mortgage rate and personal card terms.