Can I sue my joint tennant for unpaid rent

RHemmings

If the OP's partner refuses to move out, then the OP can apply for an occupation order to have the tenancy transferred into their name alone. They'd then be able to end the tenancy and move out. 

However, this is typically done in situations where (e.g.) children are at risk, e.g. if there is violence or abuse. If such does not exist, then getting an occupation order may be slow and/or difficult. However, the option is there.

As suggested above, talking to charities and organisations about the situation is a good idea. 

Is this in England? I was quite surprised to read the following on the Shelter website. This is for joint tenants. I find the bit I've bolded to be most surprising. Is this true? 

https://england.shelter.org.uk/housing_advice/private_renting/joint_tenancy_relationship_breakdown

Ending a rolling or periodic tenancy

It's easier to end a rolling or periodic tenancy. You do not need your ex's agreement.

But think about and discuss this step with you ex if you can.

The tenancy will end for both of you. Your landlord could evict anyone still living there by changing the locks when they're out.

Bookworm225

RHemmings said:

Is this in England? I was quite surprised to read the following on the Shelter website. This is for joint tenants. I find the bit I've bolded to be most surprising. Is this true? 

I can't be bothered to research the legal basis, but in principle the (pro tenant) Shelter website is not known for putting up incorrect info when it comes to "straightforward" legal matters.

RAS

This turns previous advice on it's head.

If the tenancy has been surrendered, and the other tenant isn't entitled to stay, they'd be a trespasser?

Not that this has been the way the situation has been discussed in previous threads on MSE. Perhaps there is some recent case law preventing the departing tenant from being liable for the "amount equivalent to double rent".

Based on this, the important thing is that @Deejha21 does NOT give notice to leave at the end of the fixed tenancy. She has to give notice to terminate the following rolling or periodic tenancy. 

So she will find herself paying one month or more of the periodic tenancy.

She may want to find out who the lead tenant for the deposit is but I'd assume that however the ex leaves, the property is not going a good condition?

OP, the issue of giving notice to leave a tenancy after one month of a periodic tenancy has led to a lot of discussion on MSE. I'd suggest you get chapter and verse from Shelter.