Ask a category manager what one extra day of payment terms is worth to their company. Most will say longer is better and leave it there. A few will guess. Almost nobody has a dollar figure, and negotiating days is a large part of the job.
We think that is the biggest hole in how terms get negotiated. Procurement walks into the room holding a currency it has never priced. The supplier has priced it, because the supplier's finance team lives with the cost of waiting.
The arithmetic fits on a napkin
The figures here are invented, but the sums are real. Say you spend $6M a year with a supplier. Divide by 365 and you pay them about $16,400 a day. Move from net 30 to net 60 and you hold roughly $493k of their money for thirty more days.
Your finance team has a cost of capital, the return it demands on cash. Call it 8%. Then those thirty days are worth about $39,500 a year to you. That is the whole case for asking, and the ceiling on what to pay for it.
Hold the ceiling in your head. $39,500 is 0.66% of the spend. A supplier who agrees to net 60 and adds 1% to the price has charged you $60,000 for days worth $39,500. Plenty of buyers sign that deal and book the extension as a win. Run the same sum for each supplier before you start. It takes ten minutes and a spreadsheet.
The supplier already did the sum
Now stand on the other side. Net 60 means the supplier carries about $986k of receivables instead of $493k. If they borrow at 11%, the extra thirty days costs them roughly $54,000 a year.
They will not say that number out loud. They will say "that's difficult for us," and the cost turns up in the next quote. A buyer without a number cannot tell whether a 1% rise is a fair price for the days or an opening bid.
Payment terms are a trade in days. If you cannot price a day, you cannot tell a good trade from a bad one.
Early pay runs the other way
The classic term is 2/10 net 30. Pay in ten days and take 2% off. Pay in thirty and pay the full invoice. Taking the discount means paying twenty days early, and the return on that is about 37% a year. The sum is 0.02 divided by 0.98, scaled by 365 over 20.
No treasury desk earns 37% on spare cash. Passing on 2/10 net 30 amounts to borrowing from your supplier at that rate. Supplier finance teams know the figure. A buyer who has never worked it out can sit on a discount worth more than most of what the category team will find in the quarter. Ask your accounts payable team which suppliers already offer it. You may find discounts sitting unclaimed.
Early pay is also the best thing you can offer a supplier who pushes back on days. A firm with cash pressure will often take 2/10 over a price concession. We cover the mechanics in our 35-day payment-terms essay.
Check which day the clock starts
Net 60 from what? An invoice can be dated the day goods ship, the day they arrive, or the day someone finally sends it. Terms can run from the invoice date, from receipt of goods, or from the day your system accepts the invoice. The gap between the first and the last can be two weeks.
A category manager who has run this negotiation a few times asks the question before agreeing to anything. Two weeks on $6M is about $230,000 of cash at any moment, worth roughly $18,000 a year at 8%. That prize is bigger than many price conversations, and it sits in a clause nobody reads.
Fix the start date in the contract. Write it as an event your own system records, so nobody argues about it in month four. Then check that your accounts payable team pays on day sixty and not on day forty-five because the batch run is convenient.
Ask treasury for one number
Before the next terms conversation, call treasury. Ask what rate they use to judge cash, as a percentage. They have one, because it sits behind every capital request. Multiply spend by days by that rate, divide by 365, and write the answer on the first page of your plan.
Three changes cover most of it. Put the dollar value of a day on every terms discussion. Price any extension against any price rise that comes with it, line by line, before you agree to either. And offer early pay by name when a supplier resists on days, so the trade is on the table where both sides can see it.
Some suppliers will still say no. Then you will know what no costs you, and that beats guessing. We think too many terms deals get judged on days alone, when the price attached to them decides whether the deal was good.
Why a limit on terms needs a price on it
In Autonomous Negotiation, you set a target and a limit, and the agent works between them, giving on one term to win another. A trade is only as good as the limit behind it. A limit on terms that nobody has priced is a guess with a number attached, and the agent will faithfully work inside the guess.
So we would rather start a payment-terms goal with the cost of a day than finish it without. A supplier that offers sixty days for a 1% rise is running a calculation. We want your team running one too. We think procurement should own the number, not wait for finance to hand it down.
The Whispor team
Related: 35 days: the payment-terms benchmark you can actually move · Negotiated savings aren't savings until finance can book them. · Suppliers price your switching cost, not your spend.