Microsoft account won't accept my card when buying Minecraft on a Mac

if it keeps declining, buy it on minecraft.net directly instead of through the launcher or the Microsoft Store, the checkout is a bit different. or pick up a Minecraft or Microsoft gift card from a shop and redeem it on the account. gets around the card problem completely.

Is the country on your Microsoft account the same as the country the card was issued in? That mismatch is the most common reason, and it won't tell you that's the problem. After that, the billing address has to match what the bank has on file exactly, including the postcode. Prepaid and some debit cards also get rejected for no clear reason. If it all looks right, ring the bank, they sometimes block the charge as suspicious and Microsoft just sees a decline. Paying with PayPal is a good workaround if your account offers it.