Assigning rental income to spouse who is not on mortgage or deeds

Hello
I have been reading lots of posts and finding conflicting information - I have also called 3 accountant / tax advisors and been given varying information.
I would like to confirm on here if I can. I am the sole owner of a BTL property and it is only my name on mortgage and deeds. I'd like to assign a % of the rental income to my husband who is not on the mortgage.
1 - I have been advised by one accountant that this only possible if he is on the deeds and mortgage and it is not possible to share rental income for tax purposes otherwise.
2- another accountant confirms that rental income can be shared via declarations of trust / deed of some sort and it is on the tax relief on the mortgage payments that he cannot declare - and I can only declare for the % of beneficial interest I retain. I.e. if we split rental income 90/10 - then I can only claim tax relief for 10% of the mortgage interest payments.
Reading the forum posts, option 2 seems to be the one that is correct. Is someone able to confirm this.
Lastly, I assume and I solely own the property a Form 17 is not required.
Thanks

Hi bec123 S
Based on the information provided within your question option 2 would be the correct action to take.
As you are the sole owner of said property, by completing and submitting the valid Declaration of Trust, you would assign a specific % to your Husband in terms of beneficial interests in rental income, whilst retaining the legal ownership of the property. 
Additionally, based on the % split, you would only then be able to claim for that amount in terms of mortgage interest. 
As you are the sole owner of the property, a Form 17 declaration would not apply. 
Thank you