TSEM9842 | Property held jointly by married couples or civil partners: Form 17 rule: introduction
From HM Revenue & Customs · Trusts, Settlements and Estates Manual
Married couples and civil partners can, in certain circumstances, ask to be taxed on their actual entitlement to income from jointly held property. They do this by making a joint declaration of unequal beneficial interests and submitting it to HMRC. A valid declaration under ITA/S837 overrides the 50/50 rule in ITA/S836. In the absence of a valid form 17 declaration, the 50/50 rule applies.
The declaration must be made on form 17.
A form 17 declaration must be made jointly. If one spouse or civil partner does not want to make a declaration both must accept the standard 50/50 split for jointly held property.