Thanks for your question
Unless the property is in joint names, then I am afraid the total rental income, and relevant expenses must be declared by you.
Then the first £9440 is tax free assuming you are a UK citizen (as you are still entitled to UK personal allowances, despite not being UK resident) then the remainder would be liable to 20% tax.
I should also point out, that the tax should be deducted from the rents unless you have registered for the non resident landlord scheme - I have added a link here that advises more on this topic, but as you can see, either the tenants (or managing agent if you have one) should be making these deductions and paying them over to HMRC (and then you claim the tax paid on your self assessment tax return)
The only way that you can have your wife be responsible for half the rents (and expenses) to then utilise another £9440 personal allowances (which would render the net rental income tax free) is to transfer half the property into her name.
But as things stand, you are the one responsible for the full declaration of this rental income and associated expenses.
Do feel free to ask any follow up questions.