50% cashback on your card: how to calculate what you really save

A 50% cashback is almost never a 50% discount, because it almost always has a cap. With 50% cashback and a ₲100,000 cap, if you spend ₲600,000 you get back ₲100,000, not ₲300,000. Your real discount is 16.7%.

This guide shows you how to calculate the real savings of any cashback, how much it makes sense to spend, and why card interest can wipe out the benefit.

The real cashback formula

Real cashback = the lower of (spending × %) and the cap
Real discount = real cashback ÷ spending
Spending that gets the most out of the promo = cap ÷ %

Example with 50% cashback and a ₲100,000 cap:

The more you spend, the lower the real discount. The optimal spending is ₲200,000 (100,000 ÷ 0.50): beyond that you gain nothing extra.

Two different promos: which pays more?

Imagine two promotions:

• Promo A: 30% cashback with a ₲150,000 cap.
• Promo B: 10% cashback with no cap.

If you spend less than ₲1,500,000, promo A pays more. If you spend more, B does. The rule: the bigger the spending, the better the promo with no cap.

Cashback with a cap or a direct discount: which is better?

A high cashback with a cap sounds better than a small discount with no cap, but it depends on the spending. Let's compare a 50% cashback with a ₲100,000 cap with a 15% direct discount:

Capped cashback wins on small purchases and the direct discount wins on large ones. The crossover point is the cap divided by the direct discount: 100,000 ÷ 0.15 = ₲666,667.

The five traps of a cashback

1. The cap. It's the most important fine print. Always read it before you buy.
2. Terms of use. Minimum spending, merchants, days or categories where it applies.
3. When and how it's credited. Ask on what date they return the money and what conditions apply to receive it (for example, being up to date with payments).
4. Buying what you didn't need. If you overspend ₲200,000 to receive ₲100,000, you lose ₲100,000. Cashback is only savings if the purchase was already in your plan.
5. The card's interest if you don't pay in full. It's the trap that costs the most.

When interest eats the cashback

If you pay the full statement balance on time, the cashback is profit. If you leave a balance unpaid, the card charges interest.

The Central Bank of Paraguay sets a maximum: in October 2026, interest on credit cards in guaraníes can't exceed 19.62% effective annual. Your card may charge less, but let's take that maximum as a reference:

• An unpaid balance of ₲1,000,000 generates about ₲15,000 in interest per month.
• In a little over 6.5 months, that interest equals a ₲100,000 cashback.

And if you pay only the minimum, the balance goes down very slowly. According to the BCP's card rules (reported in 2016), the monthly statement must detail the nominal and effective rates, fees and charges, and warn about the risk of paying only the minimum. Check that your statement includes them.

Six questions before buying for a cashback

• What's the cap per purchase and per month?
• Is there a minimum spend to receive it?
• At which merchants, days and categories does it apply?
• When and how is it credited?
• How much does it cost me to keep the card (annual fee and charges)?
• Will I pay the full statement balance?

If any answer is "I don't know", you don't have the full picture yet.

Full example: supermarket cashback

A supermarket offers 20% cashback with a cap of ₲50,000 per month.

• Optimal spending: 50,000 ÷ 0.20 = ₲250,000 per month.
• If you do your month's shopping for ₲250,000, the real discount is 20%.
• If you buy ₲1,000,000 a month, the cashback is still ₲50,000: a real discount of 5%.

The practical conclusion: use the promo with the spending you already had at that store and don't change your purchases to reach the cap.

A three-step method to evaluate any promo

1. Calculate the real discount with your usual spending, not with the maximum spending in the ad.
2. Check the terms: cap, minimum spend, merchants, days and crediting date.
3. Ask yourself if you'd buy it anyway without the promo. If the answer is no, you're not saving: you're spending.

Mini glossary

• Cashback: money returned to you after the purchase, usually with a cap.
• Cap: the maximum they return per purchase or per month.
• Minimum spend: what you have to spend for the promo to kick in.
• Crediting: the moment the cashback shows up in your account or on your statement.
• Direct discount: a reduction applied to the price at the moment you pay.

Calculate the real cashback of your promo

Enter your spending, the percentage and the cap. The calculator tells you how much they return, your real discount and the maximum spending that makes sense.