Compare the money saved with the cost of paying earlier
For a purchaser, a supplier’s early-payment discount should be tested against the incremental cost of advancing the payment date and the remaining cash headroom. A quoted 2% saving is not an annual return. Conversely, a high annualised percentage is not sufficient reason to exhaust essential liquidity. This is an internal management-analysis framework reviewed on 24 October 2026, not a statutory valuation, financial-statement measurement or permission to delay a legally due payment.
The ICAI Board of Studies working-capital material, Management of Payables, page 56 describes early-payment terms and the annual cost of forgoing a discount. The model below applies that financing principle to original invoice examples. It uses a stated 365-day year and simple actual-day funding unless expressly comparing an effective annual rate. GST, withholding, tax deductibility and financial-statement classification are excluded from the amounts in these examples and require their own working.
Define the terms precisely
“2/10, net 30” normally describes a 2% discount if payment occurs by day 10, with the full amount due on day 30. Confirm the actual contract: the starting date, calendar or working days, bank cut-off and whether payment must reach the supplier by the discount date. Using an invoice date where the contract starts from goods acceptance can move the entire decision. A disputed invoice or a missed cut-off is not a confirmed discount opportunity.
| Input | Meaning | Model control |
|---|---|---|
| F | Full eligible invoice amount | Use the part that actually qualifies for discount. |
| d | Discount as a decimal | For 2%, use 0.02, not 2. |
| t | Days payment is accelerated | Compare the feasible discounted date with the contractual full-payment date. |
| r | Marginal annual funding or opportunity rate | Use the cost of the cash actually committed, on the same stated day basis. |
| C | Incremental fees and other cash costs | Include only amounts caused by the early-payment decision. |
Use the net payment as the funding amount
Discount saved = F × d. Early payment = F × (1 − d). For the additional credit period t, the simple periodic cost of forgoing the discount is d ÷ (1 − d). A simple annualised equivalent is [d ÷ (1 − d)] × 365 ÷ t. It is an annualised comparison, not cash interest that the supplier necessarily invoices.
Where borrowing funds the early payment, the incremental simple financing cost is F × (1 − d) × r × t ÷ 365. Net benefit = F × d − financing cost − C. Compare alternatives on the same endpoint: at the normal due date, the loan principal and incremental financing/fees are the cost of paying early, while the full invoice is the cost of waiting. This avoids charging interest on the full invoice when only the discounted amount was advanced.
Separate nominal annualisation from compounding
An effective annual equivalent can be calculated as [1 ÷ (1 − d)] raised to the power 365 ÷ t, less 1. This assumes the same opportunity can be repeated and reinvested over the year; it is not a forecast that a one-off invoice will produce that annual cash profit. Do not compare an effective annual number with a nominal borrowing quote without aligning compounding, day basis and fees. The direct dated-cash comparison is usually easier for an approval decision.
Find the break-even discount and the cash limit
With no incremental fees and the same simple-funding assumptions, set discount saved equal to financing cost. If k = r × t ÷ 365, the break-even discount is d = k ÷ (1 + k). The denominator matters because a larger discount reduces the cash funded. If fees apply, solve the full invoice-specific equation instead of reusing the fee-free threshold.
Available cash is not automatically free. Use an evidenced opportunity cost where cash has another use, and reserve money for payroll, taxes, critical suppliers and other committed payments. Present a separate cash floor and forecast rather than treating a bank balance as unrestricted headroom. A profitable discounted payment may still fail the liquidity test. Do not count assumed bank availability until the facility and drawdown timing are confirmed.
Prioritise invoices without confusing value with accounting profit
An invoice-level MIS should show eligibility, full amount, net early payment, dates, days accelerated, funding rate, incremental fees, cash benefit, cash required and approval status. Rank feasible choices by the relevant constrained objective. Annualised return alone does not optimise a cash-limited portfolio: invoice size, minimum cash reserve and timing can prevent the highest rate from being the best implementable combination.
Measure actual discounts captured and compare them with the model. A supplier denying the discount because payment arrived late can leave both the full invoice and financing cost payable. Keep the decision calculation separate from accounting presentation: a discount is not automatically a particular expense classification, and a supplier credit note is not automatically a GST reduction. Check statutory payment limits and contractual due dates independently; this model does not recommend unlawful payment extensions.
Worked illustrations
These illustrations use fictional facts and expressly stated assumptions. Amounts are Indian rupees unless a different currency or unit is specified. They are independent examples, not findings about any actual client.
Illustrative example 1: Annualise a 2/10, net-30 offer
For a qualifying invoice of ₹10,00,000, the discount is ₹20,000 and early payment is ₹9,80,000. Acceleration is 30 − 10 = 20 days. Periodic cost of forgoing is 20,000 ÷ 9,80,000 = 2.0408%. Simple annualised cost is 37.2449%; effective annual equivalent is 44.5853% under the repeat-and-reinvest assumption. Neither annualised percentage is the actual rupee saving on this single invoice.
Illustrative example 2: Borrow at 12% to capture the same discount
Using the preceding terms and a 365-day simple interest basis, funding ₹9,80,000 for 20 days at 12% costs ₹6,443.84. Net benefit is ₹20,000 − ₹6,443.84 = ₹13,556.16 before any fees or tax effects. The normal due-date repayment would be ₹9,86,443.84 compared with the ₹10,00,000 full invoice.
Illustrative example 3: A small discount over a longer gap can lose money
For ₹5,00,000 on 1/10, net 60 terms, discount is ₹5,000, early payment ₹4,95,000 and acceleration 50 days. Forgone-discount cost annualises simply to 7.3737%. At 10% simple annual funding, interest is ₹6,780.82, so early payment loses ₹1,780.82 before fees. The discount percentage alone gives the wrong impression.
Illustrative example 4: Include a fee rather than ranking only by rate
For the ₹10,00,000, 2/10, net-30 invoice, assume 15% funding plus an incremental ₹10,000 processing cost payable at the normal due-date comparison point. Interest on ₹9,80,000 for 20 days is ₹8,054.79. Net benefit is ₹20,000 − ₹8,054.79 − ₹10,000 = ₹1,945.21. A fee quote must be incremental and verified; an already incurred unrelated annual fee should not be counted again.
Illustrative example 5: Calculate the fee-free break-even percentage
At 12% funding for 20 days, k = 0.12 × 20 ÷ 365 = 0.0065753425. Break-even d = k ÷ (1 + k) = 0.0065323898, or 0.6532%. This is the discount percentage on the full invoice, not the periodic financing rate on the smaller net payment. The threshold changes with fees or different payment dates.
Illustrative example 6: Reserve cash and evaluate each invoice
Assume cash is ₹3,00,000 with a ₹1,00,000 required reserve, leaving ₹2,00,000 deployable. Invoice A is ₹2,00,000 with 2% discount for 20-day acceleration: net payment ₹1,96,000, saving ₹4,000 and 12% opportunity cost ₹1,288.77, giving ₹2,711.23 benefit. Invoice B is ₹1,00,000 with 1% discount for 50 days: net payment ₹99,000, saving ₹1,000 and opportunity cost ₹1,627.40, giving a ₹627.40 loss. Paying A leaves ₹1,04,000 cash and meets the reserve; paying both would require ₹2,95,000 and breach it. B is unattractive even before that liquidity restriction.
Ten-step verification table
| Step | Verification | Evidence to retain |
|---|---|---|
| 1 | Confirm discount entitlement and qualifying amount | Supplier terms, accepted invoice and exclusions |
| 2 | Establish feasible payment and due dates | Contract start event, cut-offs and payment calendar |
| 3 | Calculate the days accelerated | Consistent date difference and day-count basis |
| 4 | Compute the actual net payment | Full amount less eligible discount |
| 5 | Determine marginal cash cost | Bank quote or documented opportunity rate |
| 6 | Include incremental fees and constraints | Drawdown charges, minimum fees and facility terms |
| 7 | Calculate benefit and comparable annualisation | Direct cash comparison with consistent compounding |
| 8 | Test cash floor and other commitments | Dated forecast and restricted-cash exclusions |
| 9 | Approve payment and retain eligibility proof | Authorisation and supplier receipt confirmation |
| 10 | Compare actual captured benefit with the forecast | Discount evidence, funding statement and missed-opportunity report |
Sixteen practitioner FAQs
1. Is a 2% discount the same as a 2% annual return?
No. It is a saving for paying earlier by a particular number of days. Annualisation requires that time interval and the net amount advanced.
2. Why divide by the discounted payment?
The extra credit obtained by forgoing the discount is the net amount otherwise payable early. Using the full invoice understates that periodic financing cost.
3. Does the supplier charge the annualised cost as interest?
Usually this is an analytical equivalent, not an actual interest invoice. The cash saving is the discount the purchaser validly captures.
4. When should a 360-day year be used?
Use the agreed or chosen convention consistently. These examples use 365; change both the borrowing comparison and annualisation if the decision requires another basis.
5. Which dates determine the acceleration period?
Use the feasible qualifying payment date and the normal contractual payment date, respecting the actual starting event and receipt cut-off.
6. Can the invoice date always start the discount clock?
No. Terms may refer to receipt, acceptance or another event. Read the agreement and resolve uncertainty before claiming the saving.
7. Should interest be computed on the full invoice?
For the simple model here, finance the actual discounted early payment. Additional fees or funding mechanics need their own cash-flow treatment.
8. Is an unused annual facility fee incremental?
Not if it is already incurred and unchanged by this decision. Include additional costs caused by the payment, avoiding both omission and double counting.
9. Is available cash costless?
It may have an alternative use and must preserve essential liquidity. Use an evidenced opportunity cost and a separate cash reserve test.
10. Does a positive net benefit guarantee approval?
No. Eligibility, cash headroom, operational risk, borrowing availability and legal payment requirements can prevent implementation.
11. Why can the effective annual rate exceed simple annualisation?
It assumes repeated opportunities with reinvestment. A one-off invoice does not by itself deliver that annual compounded return.
12. Can the fee-free break-even formula include a processing charge unchanged?
No. Solve the full cash-benefit equation when fees apply; the simple threshold explicitly excludes them.
13. Should invoices always be ranked by the highest annualised rate?
No. A constrained portfolio also depends on absolute cash benefit, required payment amounts, dates and the minimum reserve.
14. Does a discount automatically reduce GST?
No. This MIS excludes GST effects. Apply the relevant tax and documentation rules independently rather than assuming a commercial saving changes tax.
15. Is a cash discount always a finance expense in the books?
This decision model does not prescribe a financial-statement classification. Apply the relevant accounting framework and actual contractual facts.
16. What if payment reaches the supplier after the cut-off?
Reassess whether the discount was earned. Record the lost saving and any financing cost actually incurred, and improve the payment-calendar control.
Conclusion
Approve a supplier discount from a dated cash comparison, confirmed eligibility and a viable cash reserve. Record the real rupee benefit separately from annualised financing equivalents and reconcile the eventual discount and funding cost to the approved model.