What if my spouse doesn't have a social security number?

[santorini55]

What do I fill out if my spouse has applied for his social security card however he hasn't received it (or his number yet)?

[Opus 17]

Wait for the SSN to arrive.  If it arrives after April 18, you can file a request for an automatic extension of the deadline to October 18.

There is a procedure to file without it and apply for an ITIN instead, but you may lose certain tax benefits, and if your spouse is eligible for an SSN and has already applied, the best thing to do is just wait for it.