When you know and understand the inner workings of another department, you gain experience in a line of work that might not be your forte. You'll be able to enhance your skill sets, which will prove instrumental when you're looking to progress in your career or even transition into a new line of work.
It also makes you more marketable in your field. This isn't just applicable when you're looking for a new job, but it can even be useful for the role you're currently in. You'll be better suited to climb the ladder if you can take on more varied responsibilities.
Besides that, you'll also save a ton of cash simply because you don't have to fork out money to learn new skills. You'd be able to not only learn them but also put them into practise in your current organisation. Partnering with another department allows you to gain insight into how things are done; giving you the chance to discover what works and use it in your own department.
It is sometimes easy to forget that other departments exist when you're so focused on getting your own work done. But remember, looking beyond your department is a great step to take to develop your skills and harness them in ways that can benefit both you and your company.
Gain experience in different aspects of the company
Makes you more marketable
You get to save money