Yes, you can file separately when you are married and have the same address. And, it is true that filing separately can protect your refund from being garnished for your spouse's debts.

But, there is another way you can protect your portion of a refund if you decide to file jointly. It is called an Injured Spouse form and is used protect his or her share of the joint refund in case it gets seized or offset due to the other spouse's debts or unpaid obligations.

Generally, filing jointly will give you a bigger refund or less taxes due. When you file separately, your tax rate is higher and you won't be able to claim certain deductions or credits that are only available if filing your return jointly.

Here is information on filing separately versus jointly:

https://ttlc.intuit.com/replies/3288477

And here is information on filing an Injured Spouse Allocation:

https://ttlc.intuit.com/replies/3326788