I got this question recently:
“I have just completed my first script with another writer. We’re both unpublished writers, and I was wondering how you handle a query letter if there is more than one writer.”
What I do for scripts that I’ve written with other people is I write the query letter from my perspective. I sign it and I write as if I (not we) am talking to the producer. I’ll mention the other writer if it adds value to the pitch. If he worked as a policeman and the script is a police drama that should be mentioned. If he’s done stand-up comedy and the script is a comedy I might mention it by writing something like this, “My writing partner on this project, Joe Schmoe, has done stand-up comedy for years and is a member of the Groundlings in Los Angeles.”
In the query letter stage it’s really not that important if you have a co-writer or not so you don’t need to explicitly mention it unless mentioning it adds value to the pitch.
The producer might want you to sign a release form in which case all writers would need to sign it.
I usually include a brief synopsis with my query letter and I’ll list all writers on the synopsis at the top with the title of the synopsis like this:
You Screenplay Title
by
Joe Smith & Mary Jones
If you have any questions about how to write a query letter you should read my post How to write a professional query letter for your screenplay.
In addition, I’ve written many posts on query writing. You can find them all here: https://www.sellingyourscreenplay.com/tag/query-letters/.
Also, don’t forget that both of you wrote it. Never dimish the other writer in the query letter.
The more expeienced writer of the two must send out the query and credit their name first.
Don’t forget! Both you you wrote it and BOTH own the script’s copyright. Both must sign over the copyright to the producer/production company.