The sales review was a celebration. Revenue was up, targets were met and the board deck showed a rising line. But one comparison did not fit: gross margin had fallen for three quarters in a row. Nobody had questioned it because the focus was on volume. An internal audit review found discounts given without proper approval, pricing deviations nobody tracked and sales incentives paid on turnover regardless of profit. This article explains how to analyse margin erosion, separate price, volume and cost effects, and put controls on discounts and incentives so that growth adds value instead of quietly eroding it.
Margins fall while revenue grows when extra sales come from deeper discounts, a shift to lower-margin products or customers, or costs rising faster than prices. Margin analysis separates these effects through a price-volume-cost bridge. The controls that fix it are a discount approval matrix, margin-based (not only revenue-based) reporting, tracking of pricing deviations and sales incentives linked to contribution margin.
Why growth can hide margin erosion
Revenue is the number everyone watches. It is reported daily or weekly, it drives sales targets and incentives, and it is easy to explain. Margin is reported later, often monthly or quarterly, and usually at an overall level. By the time the decline is visible, it has been happening for months.
Erosion often comes from many small decisions: a salesperson offering an extra 3% to close an order at month-end, a regional manager matching a competitor's price without telling anyone, or a scheme designed to push volume in a slow quarter. Each decision makes sense in isolation. Together, they shift the business towards lower-value sales.
Revenue leakage through unapproved credit notes and billing errors is a related problem, covered in our article on revenue leakage controls. This article focuses on margin: whether the sales the business is choosing to make are worth making.
Common causes of falling margins
How to analyse margins: the price-volume-cost bridge
A margin bridge splits the change in gross margin between two periods into its drivers, so management can see which part came from selling more, which from selling cheaper and which from costs. At a simple level:
- Volume effect = change in units × previous margin per unit.
- Price effect = current units × change in selling price per unit.
- Cost effect = current units × change in cost per unit (shown as negative if cost rises).
In practice, the bridge is run by product, customer, region and salesperson, and a mix effect is added to show how much of the change came from a shift between higher and lower-margin items. Analytics on the invoice-level sales register, joined with standard or actual costs, is enough to start.
A company sells one product line. Last year: 10,00,000 units at ₹100, cost ₹70, gross margin ₹30 per unit, total margin ₹3.00 crore on revenue of ₹10.00 crore (30%). This year: 12,50,000 units at an average ₹94 after discounts, cost ₹71, margin ₹23 per unit. Revenue is ₹11.75 crore (up 17.5%), but gross margin is ₹2.875 crore (24.5%), down ₹12.5 lakh.
Bridge: volume effect 2,50,000 × ₹30 = +₹75 lakh; price effect 12,50,000 × (−₹6) = −₹75 lakh; cost effect 12,50,000 × (−₹1) = −₹12.5 lakh. Net: −₹12.5 lakh. The extra volume was entirely paid for by discounts, and the cost increase was not passed on.
Controls that protect margins
| Control | How it works | What internal audit checks |
|---|---|---|
| Discount approval matrix | Discount bands with approvers at each level, based on discount percentage and, ideally, resulting margin | All discounted invoices against the matrix; approvals recorded before invoicing |
| Floor price or minimum margin | System blocks sales below a set margin unless a senior approver overrides | Configuration, override log and who can change floor prices |
| Price list revision | Prices reviewed when input costs move beyond a trigger | Timeliness of revisions against cost changes |
| Margin reporting | Monthly margin by product, customer, region and salesperson | Reports exist, are reviewed, and lead to action |
| Pricing deviation tracking | Exception report of all sales below list price with reasons | Completeness of the report and follow-up on repeat deviations |
| Incentive design | Sales incentives linked to contribution margin or realised price, not only revenue | Incentive calculations and whether they reward low-margin sales |
The Audit Committee's oversight of internal financial controls under Section 177(4)(vii) of the Companies Act, 2013 is not limited to accounting entries. Pricing and discount authority affect reported revenue and profit, and a weak framework is worth reporting to the committee.
Red flags of silent margin erosion
- Revenue growing faster than gross margin for two or more consecutive periods.
- Average realised price per unit falling while list prices are unchanged.
- Discount approvals bunched at month-end or quarter-end.
- A few salespersons or regions consistently below average margin.
- Large customers whose margin after freight, credit and returns is close to zero.
- Sales incentives rising faster than gross margin.
- Discounts approved by email or phone with no system record.
Growth bought with discounts also matters when a business is valued or sold. Buyers look closely at whether margins are sustainable; see our article on sustainability of earnings, growth and margins.
Aligning sales incentives with profitability
People respond to what they are paid for. If incentives reward revenue alone, discounting is a rational way to hit targets. Some practical design choices:
- Add a margin gate. Pay incentives only if the salesperson's average margin is above a threshold.
- Weight by contribution. Calculate incentives on contribution margin, or on revenue adjusted for discount given.
- Pay on collection. Link payout to cash collected, so long credit terms are not used to win sales.
- Claw back. Adjust incentives for later credit notes, returns and bad debts on the same sales.
- Share the data. Give sales teams their own margin reports, so they see the effect of each discount.
Internal audit should test whether the incentive scheme as calculated matches the approved policy, and whether the policy itself encourages the right behaviour.
Margin analysis and discount control checklist
- Gross and contribution margin reported monthly by product, customer, region and salesperson.
- Margin bridge prepared each quarter separating volume, price, mix and cost effects.
- Approved discount matrix in place and enforced in the ERP.
- Floor price or minimum margin rules configured, with override log reviewed.
- Pricing deviations tracked in an exception report with reasons.
- Price lists revised in line with input cost changes, with trigger points defined.
- Cost to serve (freight, credit days, returns) considered for major customers.
- Sales incentives linked to margin or realised price, with claw-back for returns.
- Month-end and quarter-end discount spikes investigated.
- Findings reported to senior management and the Audit Committee and tracked to closure, as set out in our internal audit and corporate governance guide.
Frequently asked questions
Why do margins fall when sales increase?
Usually because extra sales are won with higher discounts, the mix shifts towards lower-margin products or customers, or costs rise without matching price increases. A price-volume-cost bridge shows which of these is driving the decline.
What is a discount approval matrix?
It is a policy that sets who can approve discounts of different sizes, for example a sales manager up to a set percentage and the sales head or CFO beyond that. It works best when enforced in the billing system and linked to the resulting margin.
What is price-volume-mix analysis?
It is a method of explaining the change in revenue or margin between two periods by separating the effect of selling more or fewer units, changes in selling price, changes in product or customer mix, and changes in cost.
How should sales incentives be designed to protect margins?
Link incentives to contribution margin or realised price rather than revenue alone, add a minimum margin condition, pay on collection and claw back incentives for returns and credit notes on the same sales.
How often should margin analysis be done?
Management should review margin reports monthly, with a fuller bridge analysis each quarter. Internal audit can test the controls and reporting periodically based on risk.
Is margin analysis part of internal audit?
Yes, where pricing and discounts are significant risks. Internal audit checks whether discount authority, pricing controls and margin reporting are designed and working, and whether incentive schemes encourage the right behaviour.
Conclusion
Revenue growth is visible and easy to celebrate. Margin erosion is quiet and often noticed late. A regular margin bridge, a discount approval matrix enforced in the system, tracking of pricing deviations and incentives tied to profitability give management early warning and better control over value. Growth is worth having only if it brings margin with it.
Need a fresh look at your internal controls?
H K Davra & Co. supports companies with risk-based internal audit, internal financial controls testing and Audit Committee reporting.
Talk to usThis article is for general information only and does not constitute professional advice or solicitation. Examples are illustrative. Provisions are summarised as of October 2026. Please refer to the relevant provisions and seek advice on your specific facts.