Maintaining 50/50 beneficial ownership when taking one spouse off the title deed

Hi, My wife and I currently co-own a house without mortgage as joint tenants. It is rented out, and we each declare 50% of the profit in our individual tax returns. We are raising a mortgage from the property, which will be just to me, not my wife. Hence the bank requires that my wife is removed from the title deed. We would like to keep the beneficial ownership the same, a 50/50 split, so I think (from other posts and answers) we should have a deed of trust drawn up at the same time as my wife is removed from the title deed, to assign equal beneficial ownership. Could you please let me know: 1) If I am correct that this is the right way to keep our tax situation the same, and if we need to do anything other than have the deed of trust drawn up and keep it safe in case it is requested (e.g. file it with HMRC?; fill in additional forms for HMRC?). 2) If we did not draw up this deed of trust, and my wife was simply removed, would HMRC then consider that all rental income should be declared by me going forward, and our proportions worked out accordingly for the current tax year (hence something like a 75/25 split for the current tax year if we made the change (from both on the deed to one on the deed) half way through the tax year?) Thanks.

Hi bugman,
Thank you for your question.
As you are looking to take out a mortgage in just your name, removing your Wifes name from the title deed,
I would advise that HMRC would expect to see a valid Declaration of Trust outlining the benefical interest of both yourself and your Wife of the 50/50 split.
As the property is currently split between the two parties, a Form 17 would usually be sufficient, however, as she is being removed, this would no longer apply.
If a Deed/Declaration of Trust is not drawn up, then you are correct, HMRC would expect 100% of the rental income and any expenses to be incurred by yourself.
Further information on joint tenants can be found here:
Joint property ownership
Additional information of the declaration of trust can be found here:
TSEM9170 - Ownership and income tax: legal background: ownership income follows property - variation  
TSEM9160 - Ownership and income tax: legal background: ownership - income follows property
Thank you.