Why do I need a card sometimes?

[GPT_01]

I am often able to make payments from my bank account without needing to have a credit card linked to the account, but other times, seemingly without reason it will not let me make any purchases for a week or two without having a card linked to my account. Is there a reason to this?

[erik11747]

paypal needs to verify

[kernowlass]

@GPT_01 

Some merchants block other funding sources and require the safer payment option (for them) of a credit card.