You're welcome. I have no idea regarding rental income.
The purpose of my post was to highlight the current income tax exemptions. Maybe they apply to your circumstances or not. Apply them if and where necessary, if you so wish.
I will not be applying for a TIN, as I have already posted on AN. Because my UK state pension is under my 560k annual exemptions. And my military pension is covered under the DTA.
Others may decide to apply for a TIN, and that is their choice.
Everyone has a different viewpoint on this. But I will do nothing, until it is 100% necessary, if and when it is clarified, and thus instructed by the TRD.