Does he have an SSN or ITIN?

I believe they both do.

I dont see why they wouldn't file jointly

What visa type does he hold?

What income did he have in 2024 before coming to US?  Does he want to pay US tax on that also, and maybe claim foreign tax credit?  

You say "most of 2024". If you file MFJ then you both of you have to include world wide income. see pub 519 for complete info.

Thanks, I am aware of that!

Thanks. This is a potential client for now so I needed this information.

The first question is always what visa he (or they) have.  And is the wife a US citizen, or are they both "foreign" nationals.  

They are both German citizens. Moved here together and both have salaried jobs here!

Thanks!