The Sign-Up Bonus Maths That Card Blogs Never Show You

A welcome bonus is presented as a number so large it stops feeling like money. Sixty thousand points. Eighty thousand miles. It sounds less like a discount and more like a windfall.

Then you read the conditions and there are four numbers that decide whether it is a windfall or an expensive way to buy something you did not need.

Number 1: the minimum spend, and the word "anyway"

Every bonus requires spending an amount within a window — commonly a few thousand within three months.

The single question that decides everything: would you have spent that money anyway?

If yes, the minimum spend is free. Route your normal spending through the card, hit the target, take the bonus.

If no, you are buying points. And you are buying them at a price you can calculate: whatever you spent that you would not otherwise have spent. Buying 500 of things you did not want in order to earn 200 of points is a 300 loss with an excellent narrative attached.

The manufactured-spend trap is not exotic. It is mostly people buying gift cards, upgrading purchases they were going to make cheaply, and prepaying bills — all of which are fine, and none of which are free.

Number 2: the annual fee, in year one and year two

Many premium cards waive the annual fee in year one. That is a genuine offer and it changes the first-year maths completely.

It also means the honest comparison is two years, not one:

Still positive here — but notice year two is negative, and year three is negative again. A card that is excellent in year one and mediocre afterwards is a perfectly good decision as long as you make it deliberately and diarise the renewal date.

The break-even on ongoing value is the same calculation as in is a credit card annual fee worth it.

Number 3: what the points are actually worth

This is where most bonus maths quietly inflates.

Points have a range of values depending on redemption. Cash back is usually the floor. Transfer partners at good award availability are the ceiling. The number in the marketing is generally near the ceiling; the number most people achieve is nearer the floor.

Two rules that keep the estimate honest:

**Value the points at how you will redeem them, not at the best redemption that exists.** If you always take statement credit, the ceiling is irrelevant to you.

Check that the seats exist before valuing points at award-chart rates. An 80,000-mile business seat is worth a great deal if it is bookable on your dates and nothing at all if it is not. PointsYeah searches award availability across programmes in real time, which turns this from a hope into a check — and our award search walkthrough shows the method.

Background on the mechanics is in how credit card rewards work and credit card rewards explained.

Number 4: the interest risk, which dwarfs everything else

If chasing a minimum spend results in carrying a balance, the bonus is gone and then some. Card interest rates make short work of a 600 bonus.

This is not a small caveat. It is the main reason bonus chasing goes wrong, and it goes wrong most for the people who are keenest — because the bonus is most tempting when money is tight, which is exactly when the minimum spend is hardest to hit from normal spending.

The application cost nobody prices

Each application typically produces a hard search on your credit file, and the effect is usually modest and temporary — but several applications in a short period read differently to a lender than one does. If a mortgage or a loan is coming in the next six months, that is the wrong six months to open three cards.

We covered the mechanics in does applying for a credit card hurt your credit score and the broader picture in credit score explained. If you are building a file rather than optimising one, build credit from scratch and best credit cards for building credit are the right starting points — and Kovo is one of the tools we cover for establishing a file without a card.

A worked decision, start to finish

Offer: 60,000 points after 4,000 spend in 3 months. Annual fee 95, not waived.

1. Would I spend 4,000 in three months anyway? Normal spending is about 1,300 a month, so yes — comfortably, with no manufactured spending. 2. What are the points worth to me? I redeem for flights via transfer partners, and I have checked seats exist on routes I actually fly. Call it 1.2 per point at my realistic redemption, so ~720. 3. What does it cost? 95 in year one. And again in year two unless I review it. 4. Interest risk? Zero — the statement is paid in full by direct debit. 5. Net year one: ~625 positive, on spending that was happening regardless.

That is a good offer. Change any one input — spending that has to be manufactured, points redeemed at cash-back rates, a balance carried for two months — and the same offer turns marginal or negative.

Where the bonus is genuinely the best deal in personal finance

For someone who spends predictably, pays in full, and travels enough to redeem points well, welcome bonuses are one of the few places in retail finance where the customer reliably wins. That is not a myth.

It is just conditional on all three of those things being true at once. The blogs quote the bonus. The conditions are where the money is.

Related reading: minimum spend requirements explained, maximise travel rewards, and — if the card is for use abroad — The 3% Tax series, because a bonus earned and then handed back in foreign transaction fees is a wash.

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Sources

• CNBC Select — Best credit cards with no foreign transaction fees, August 2026 (fee ranges): cnbc.com
• NerdWallet — Best No Foreign Transaction Fee Credit Cards, August 2026: nerdwallet.com
• Consumer Financial Protection Bureau — Credit card interest and how balances are charged: consumerfinance.gov