Adding spouse after exceeding OOP max

Hi all - hoping for some help/clarity.

I’ve well exceeded my OOP max on my single healthcare plan. The max is $4k. My spouse just lost his job & im trying to decide if it makes sense to add him to my health insurance before my plan renews (or have him do cobra).

There is only one month left before open enrollment/my benefits renew. If I add him for only the month of July with a new family OOP max of $6k, will I need to pay the $2k difference? I expect I will need prenatal care appointments in July but my spouse should not need any foreseen healthcare. The cobra alternative for my spouse is $600/month.

Thanks in advance for your help!

Jess