Payment Timing and Trade Discount Decisions

Why This Topic Matters
Payment timing and trade discount decisions sit at the heart of corporate liquidity management because accounts payable is one of the largest and most controllable sources of short-term financing for most companies. Every invoice a firm receives presents a small financing decision: pay early and capture a discount, pay on the due date and use the supplier's money for free, or pay late and risk penalties and damaged relationships. Summed across thousands of invoices, these choices determine Days Payable Outstanding (DPO), the length of the cash conversion cycle, the amount of short-term borrowing required, and ultimately the firm's cost of capital. The AFP CTP exam tests this area heavily because it combines a precise calculation (the annualized cost of forgoing a discount) with practical judgment about working capital, supplier relationships, and the treasury professional's role in disbursement policy. Expect at least one or two questions on this topic, and expect them to require both a formula and a decision.

What It Is: Trade Credit and Discount Terms
Trade credit is the credit a supplier extends to a buyer when it ships goods or performs services and allows payment at a later date. It is spontaneous financing: it arises automatically with purchases, requires no negotiation with a bank, and carries no explicit interest. The terms of trade credit are expressed in a shorthand such as 2/10, net 30, which means the buyer may deduct 2 percent from the invoice if payment is made within 10 days (the discount period); otherwise the full invoice amount is due within 30 days (the net period or credit period).

Other common term structures you may see on the exam include:
• Net 30 / Net 45 / Net 60: no discount offered; full amount due at the end of the period.
• 1/10, net 30 or 3/15, net 45: different discount percentages and periods.
• EOM (end of month) or proximo terms: the clock starts at the end of the month in which the invoice is dated, e.g., 2/10 EOM means the discount is available until the 10th of the following month.
• Seasonal dating: the supplier delays the start of the credit period to match the buyer's selling season.
• Cash before delivery (CBD) / cash on delivery (COD): no credit is extended.
• Dynamic discounting and supply chain finance: modern programs in which the discount varies with how early the buyer pays, or in which a bank pays the supplier early at a rate based on the buyer's credit rating.

The core decision for treasury is binary: take the discount (pay on the last day of the discount period) or forgo the discount (pay on the last day of the net period). Paying on any other day is almost always suboptimal, because paying earlier than the last discount day gives up use of cash for no additional benefit, and paying between day 11 and day 29 gives up the discount while also giving up free financing days.

How It Works: The Economics of the Decision
When a buyer forgoes a discount, it is effectively borrowing from the supplier for the days between the end of the discount period and the end of the net period, and the discount it gave up is the interest on that loan. Consider an invoice of $100,000 on 2/10, net 30. The buyer can pay $98,000 on day 10 or $100,000 on day 30. Choosing to pay $100,000 means the buyer gets to keep $98,000 for an extra 20 days and pays $2,000 for the privilege. That is a 20-day interest rate of 2,000 / 98,000 = 2.04 percent, which is extremely expensive once annualized.

The Annualized Cost of Forgoing a Discount (Simple / Nominal Rate)
Cost = [Discount % / (100% − Discount %)] × [365 / (Net Period − Discount Period)]

Worked example for 2/10, net 30:
Step 1: 2 / (100 − 2) = 2 / 98 = 0.020408 (the periodic rate)
Step 2: 365 / (30 − 10) = 365 / 20 = 18.25 (the number of periods per year)
Step 3: 0.020408 × 18.25 = 0.3724, or approximately 37.2 percent

The Effective Annual Rate (Compounded) Version
EAR = [1 + Discount % / (100% − Discount %)] ^ [365 / (Net Period − Discount Period)] − 1
For 2/10, net 30: (1.020408)^18.25 − 1 = approximately 44.6 percent

The compounded figure is higher because it assumes the saved discount is reinvested each 20-day period. The CTP exam most often uses the simple annualized formula, but read the question carefully; if it asks for the effective annual rate or says the cost is compounded, use the EAR version. Also note the day-count convention: most AFP materials use 365 days, but if the question specifies 360, use 360.

Additional Quick Reference Calculations (365-day basis, simple rate)
• 1/10, net 30: (1/99) × (365/20) = 0.0101 × 18.25 = 18.4 percent
• 2/10, net 60: (2/98) × (365/50) = 0.0204 × 7.3 = 14.9 percent
• 3/15, net 45: (3/97) × (365/30) = 0.0309 × 12.17 = 37.6 percent
• 2/10, net 30 but paying late on day 40: (2/98) × (365/30) = 0.0204 × 12.17 = 24.8 percent

Notice the two levers: a larger discount percentage raises the cost of forgoing it, and a longer gap between the discount date and the net date lowers the cost because the buyer gets more days of use for the same forgone discount.

The Decision Rule
Compare the annualized cost of forgoing the discount with the firm's opportunity cost of funds, which is usually the marginal short-term borrowing rate (such as a line of credit or commercial paper rate) or, for a cash-rich firm, the short-term investment yield.
• If the cost of forgoing the discount is greater than the borrowing rate, take the discount, even if the firm must borrow to do so. Borrowing at 8 percent to avoid an implicit 37 percent cost is clearly rational.
• If the cost of forgoing the discount is less than the borrowing rate (or the firm has no access to credit at any reasonable rate), forgo the discount and pay on the net due date.
• If the firm has surplus cash earning a low short-term yield, taking the discount is almost always superior because the implicit return on paying early far exceeds money market yields.

Example: A firm with a 9 percent line of credit receives terms of 2/10, net 60. Cost of forgoing = 14.9 percent. Since 14.9 percent exceeds 9 percent, the firm should draw on the line and take the discount. If the same firm receives 1/10, net 90, the cost of forgoing is (1/99) × (365/80) = 4.6 percent, which is below 9 percent, so the firm should forgo the discount and pay on day 90.

Payment Timing Beyond the Discount Question
Treasury professionals also manage the broader timing of disbursements:
• Pay on the due date, not before. Paying earlier than required forfeits interest or increases borrowing. Disbursement systems should schedule releases so that funds arrive exactly on the net date or discount date, taking into account mail, processing, and clearing float for checks, or settlement timing for ACH and wire.
• Stretching payables (paying after the net date) lowers the cost of trade credit mathematically but carries hidden costs: late fees, loss of future discounts, tighter terms, lower credit ratings from agencies such as Dun and Bradstreet, supply disruption, and reputational damage. It is generally viewed as a short-term, last-resort liquidity tactic, not a policy.
• Days Payable Outstanding (DPO) = Accounts Payable / (Cost of Goods Sold / 365). Lengthening DPO shortens the cash conversion cycle (CCC = DIO + DSO − DPO) and reduces working capital needs, but must be balanced against discount capture and supplier health.
• Payment method selection affects timing: checks offer disbursement float, ACH settles in one or two days, wires settle same day, and cards can extend the effective payment date to the card statement due date while still paying the supplier promptly.
• Centralized payables and payment factories allow treasury to enforce consistent discount-capture policies and optimize release dates across the enterprise.

Seller's Perspective
The exam may flip the question. A supplier offering 2/10, net 30 is paying roughly 37 percent annualized to accelerate collections by 20 days. The supplier should offer a discount only if its own cost of capital, its need for liquidity, or the reduction in bad-debt and collection expense justifies that cost. Changing terms also affects the supplier's DSO and cash forecast.

How to Answer Exam Questions on This Topic
Typical question formats include:
1. Calculate the annualized cost of forgoing a discount for stated terms. Identify the discount percentage, the discount period, and the net period; plug into the formula; watch the day-count basis.
2. Decide whether to take or forgo the discount given a borrowing rate. Compute the cost, compare, and choose. The answer is usually take the discount, because most standard terms imply very high costs, but always verify.
3. Determine the optimal payment date. The answer is either the last day of the discount period or the last day of the net period, never a day in between and never earlier than necessary.
4. Compute the cash outflow on a given date, e.g., a $250,000 invoice at 2/10, net 30 paid on day 10 requires $245,000.
5. Evaluate stretching. Recalculate the cost with the longer actual payment period, and identify qualitative costs of paying late.
6. Interpret the impact on working capital metrics such as DPO and the cash conversion cycle when payment policy changes.
7. Conceptual questions on why trade credit is called spontaneous financing, why forgone discounts are an expensive form of credit, or the role of dynamic discounting and supply chain finance.

Exam Tips: Answering Questions on Payment Timing and Trade Discount Decisions
• Memorize the formula cold: Discount / (100 − Discount) multiplied by 365 / (Net days − Discount days). The denominator of the first fraction is the amount you actually pay (98, not 100). Using 100 instead of 98 is the most common error and often matches a wrong answer choice.
• Use the difference in days, not the net period alone. For 2/10, net 30, the financing period is 20 days, not 30. Distractor answers frequently use 30.
• Check the day-count basis. Default to 365 unless the question states 360. If answer choices are close together, the day count is probably what separates them.
• Know when to use simple versus effective annual rate. Words like effective, compounded, or true annual cost signal the EAR formula. Words like annualized or approximate usually signal the simple formula.
• Compare to the correct benchmark. The comparison rate is the firm's marginal short-term cost of funds or opportunity rate, not its weighted average cost of capital or long-term bond rate.
• Remember the decision logic even when the numbers favor forgoing. If the cost of forgoing is below the borrowing rate, the correct answer is to pay on the net date. Do not assume taking the discount is always right.
• Payment should be made on the last possible day of whichever period you choose. If an answer says pay immediately upon receipt of invoice, it is almost certainly wrong.
• Stretching lowers the computed cost but is rarely the recommended answer in a policy question. Expect the exam to treat late payment as a relationship and credit risk, not a best practice.
• Think from both sides of the transaction. A question about a seller offering discounts is the mirror image: the same percentage that is the buyer's implicit return is the seller's implicit cost.
• Link to the bigger picture. Be ready to connect discount decisions to DPO, cash conversion cycle, cash forecasting, disbursement float, and centralized payables, since CTP questions often embed the calculation inside a liquidity management scenario.
• Estimate before you calculate. Any discount of 1 percent or more over 20 days or less annualizes to a double-digit rate; if your computed answer is 3 percent for 2/10, net 30, you made an arithmetic error.
• Manage your time. These calculations take under a minute once practiced. Do several variations (1/10 net 30, 2/10 net 45, 3/15 net 60, 2/10 net 30 paid day 45) until the arithmetic is automatic.

Summary
Trade credit is free only until the discount date; after that it becomes one of the most expensive forms of short-term financing a company can use. The treasury professional's job is to quantify that cost with the annualized forgone-discount formula, compare it to the firm's actual cost of funds, and schedule disbursements to fall precisely on the optimal date. Master the formula, the two-day-count conventions, the simple-versus-effective distinction, and the decision rule, and you will handle every variation of this topic the CTP exam can present.