Meaning of trade: exceptions and alternatives: furnished lettings
Income from furnished lettings is rarely trading income, even when the landlord works full time running the rental business.
It is only treated as a trade when the landlord remains in occupation of the property and provides services substantially beyond those normally provided by a landlord. This will be the case, for example, where the activity consists of providing bed and breakfast, or running a hotel or guesthouse. See PIM4300 (and PIM4000 onwards if the special rent-a-room rules apply).
Rents from properties that meet the qualifying tests for furnished holiday lettings are chargeable as property income. There are special rules that apply to furnished holiday lettings, but not to other lettings, including relief for some losses on the same basis as traders. See PIM4100 onwards.