Can I get a plan with T-Mobile if my credit isn't that good?

So I'm 18 and I just started working a couple of months ago. I have an iPhone 5 that I bought on eBay and the carrier is T-Mobile. Can I get a plan with this phone or would I still have to make a huge deposit?

T-Mobile no longer does contracts (except for existing customers who have to complete their contracts).

I do not think you would have any trouble getting service with T-Mobile without a huge deposit. I think that you select the plan you want and then pay ahead of time so if you do not pay, you are not breaching the contract at all. You would simply not have service until you did pay (and after a period of time if you did not, the account would be closed).