[fer]

In France married women, if they let their guard down, will be given their husband's last name as "nom d'usage" upon almost any sign-up paperwork, without being asked, at least in my experience.

Nom d'usage technically has no legal value, it's just a last name you might want to be addressed as, normally that of your husband but it can be a pen name and whatever. It's optional, and technically only at the request of the relevant person. Men can have nom d'usage too (égalité, after all).

Still, immigration offices, banks, insurances... they often slap the husband's last name if that field is left empty, just because. Why would you want something else, right? She probably forgot!

We started crossing those fields to make it clear she doesn't want a nom d'usage.

[makeitdouble]

Yes, it's really bad.

We actually couldn't open a joint bank account with both names separated. They'd accept the papers signed in the official names, but the names on the cards and other communication needed to be unified for their system to accept it. They'd accept to reemit card with the correct names only as an exception by abusing the card renewal system apparently

[fer]

I assume you're talking about Société Générale? I've experienced that, and what's worse it's that's it's broken on purpose. A joint bank account doesn't require the people to be married, let alone to share names. But if they tick the married box, whoops, now it's suddenly mandatory.