Tin House is now accepting unsolicited submissions until October 15, 2018.
They are currently reading for all open issues as well as one upcoming theme.
Summer 2019 and Winter 2019: No theme. Submit fiction, nonfiction, and poetry.
Fall 2019: The Horror—”From the mundane frights of everyday life to the truly macabre, if it makes your hair stand on end, we want to hear about it. Send us your scariest stories, eeriest essays, and most petrifying poetry!”
Please submit one story or essay (maximum 10,000 words), or up to five poems at a time.
Only previously unpublished works will be considered for publication.
More here.