Problem Zlash Price Intelligence fixes · 2 of 4
The per-card monthly cap blindness
How the cap actually works
Every bank instant discount offer has three numerical knobs:
- Discount rate — e.g. 10% of the cart value
- Per-transaction cap — e.g. ₹1,500 on this transaction
- Per-card-per-month cap — e.g. ₹3,000 cumulative across all transactions on this card with this merchant in the calendar month
The headline %-off is the theoretical rate. The realised rate on a given transaction is min(rate × cart, per_txn_cap, monthly_cap_remaining). On a ₹50,000 cart with a 10% / ₹1,500 / ₹3,000 offer where you have already used ₹2,500 of the monthly cap this calendar month, the realised discount is min(5,000, 1,500, 500) = ₹500, not ₹5,000.
Why no one tells you the remaining cap
- The merchant does not know. The per-card monthly cap is tracked by the issuer (or the issuer's offer-management platform), not the merchant. The merchant sees the gateway approve or reject the discount on each transaction, after the fact.
- The issuer does not surface it cleanly. Issuers track per-merchant per-offer caps internally for settlement reconciliation but rarely expose a buyer-facing "cap remaining" surface in their app or statement.
- No published API. There is no public interface to query "how much HDFC instant-discount cap do I have left on Amazon this month?". Aggregators have to model it.
What this hides from the buyer
The structural consequences add up over a quarter:
- The high-AOV transaction that "cap-burns" the entire monthly allowance is invisible until it lands.
- The medium-AOV transaction earlier in the month would have realised a higher fraction of its theoretical discount, but no one asked which order to do first.
- A second card with an unconsumed cap on the same merchant would have produced a real discount; the buyer used the first card because the listing said "10% off with HDFC" without context.
None of these are visible without modelling the cap.
How Zlash Price Intelligence handles it
Zlash treats the monthly cap as a first-class input in the effective-price formula:
- The offer catalogue stores per-offer caps (per-transaction and per-month) explicitly, not just headline rates.
- The buyer's declared wallet and prior transaction history feed a remaining-cap estimate.
- The effective-price column degrades gracefully when the cap is exhausted — a card whose cap is fully used shows the listed price minus the other layers, not the listed price minus a non-existent discount.
- The matrix highlights the cards with unconsumed cap headroom so a buyer with multiple cards on the same issuer ladder picks the right one.
See cap-aware effective prices
Zlash Price Intelligence applies the remaining-cap estimate to every card in your wallet so the cheapest combination shown is also achievable.
Open Price Intelligence →