Bethesda has revealed that the Vault-Tec DLC for Fallout 4 will be released on July 26.
"Build a brighter future underground with the all-new Vault-Tec Workshop. Create a massive Vault and attract new Dwellers using pre-war industrial kits complete with retro-nostalgic furniture, lighting, and art. And like every good Overseer, run Vault-Tec approved experiments on your Dwellers to learn what makes an ideal citizen. Vault-Tec has given you the tools, the rest is up to you!" reads the DLC's description.
You can download the Vault-Tec DLC as part of the season pass.