Rent a Room Relief on Form 12 for jointly assessed couple

My wife and I have a tenant staying at primary residence. The tenant pays €900 to my wife via direct debit a month so this qualifies for the relief.

We are jointly assessed.
When completing the form 12, should I enter €10,800 as the amount for my wife or should I divide this by 2 and enter the amount for both of us?

Who owns the house?

The mortgage is in both our names and we’re married

Then it's €5,400 for each of you.