How Crypto Cards Auto-Convert Your Balance at Checkout
You tap the card, the merchant is paid in euros, and something of yours was sold to make that happen. Here is what occurs in those two seconds, and what it costs you.
What happens when you tap a crypto card?
The merchant never receives crypto. They are paid in their own currency, by the card network, exactly as they would be by any other card. What is different happens on your side of the transaction, in the moment between the tap and the approval.
| Step | What happens |
|---|---|
| 1. Authorisation | The terminal asks the card network to approve an amount in the merchant's currency. |
| 2. Balance selection | Your provider decides which of your balances will fund the charge. |
| 3. Conversion | If the funding balance is not the merchant's currency, it is sold for that currency. |
| 4. Settlement | The provider pays the network; the merchant is paid as normal. |
Which balance gets used first?
Sensible providers try the matching fiat balance first. If you are paying in euros and you hold euros, no conversion happens and no spread is paid. Only when the matching balance is short does the card reach for another currency, and then for crypto.
The order in which it reaches for crypto matters more than people expect. Selling a volatile asset to buy coffee is a decision, and it should be one you configured rather than one the app made for you.
What exchange rate do you get?
Whatever rate the provider quotes at the instant of conversion, plus whatever spread they build into it. The spread is the real cost, and it is often invisible because it is baked into the rate rather than itemised as a fee. A card advertising zero fees can still be expensive if its rate is two percent worse than the market.
If a provider will not show you the rate it used on a completed transaction, assume the spread is worth hiding.
Do you pay tax when the card converts crypto?
In many jurisdictions, yes. Selling crypto for fiat is a disposal, and a disposal can trigger a capital gain or loss — even when the fiat immediately buys a sandwich. This surprises people, because it means routine spending can generate a long list of small taxable events.
Rules differ substantially by country, and some have de minimis thresholds for small transactions. This is a genuine reason to prefer spending a stablecoin or a fiat balance over spending an appreciated asset. It is also a reason to talk to an accountant rather than to a blog.
What happens with a refund?
The merchant refunds the fiat amount they were paid. You are made whole in currency, not in the asset you originally sold. If you sold an asset at one price and the refund arrives after that asset has risen, you receive fewer units back than you gave up. Conversion is not reversible just because a purchase is.
Is a crypto card just a debit card?
Mechanically, yes, and that is a feature. It works everywhere the network works, the merchant needs to know nothing, and you are covered by the same scheme rules on disputes. The crypto part is a funding detail, not a different payment system.
How Pulsar's card works
Pulsar checks your matching fiat balance first, then other fiat, then crypto in an order you set. Conversion happens at the moment of purchase and the rate used is shown on the transaction. Pulsar is in closed beta — join the waitlist for early access.
