Not always. You can operate a bed and breakfast from your home (meaning your permanent residence) without the need for planning permission, depending on what proportion of your home will be utilised by the bed and breakfast operation.
Planning permission will not be required if the primary use of the dwelling remains that of your home. There must not be a material change of use of the dwelling having regard to the number of rooms used for the bed and breakfast operation and the ancillary functions associated with it.
For example, one bedroom in a three bedroom dwelling could be used for bed and breakfast accommodation without resulting in a material change of use. The use of two bedrooms and a separate sitting/dining room for bed and breakfast accommodation would amount to a material change of use and therefore planning permission would be needed.
Another way of sharing your home to generate additional income without the need for planning permission is to rent it out when you are away from the island as a short term holiday let. This can be done subject to certain limitations. These are that the dwelling can only be let for a period of six to eight weeks over the course of a single calendar year and on the proviso that any period of letting does not exceed a continuous period of 28 days.
You should note that even though planning permission is not required in the above circumstances, there may be a separate requirement for permissions from Building Control and also the Committee for Economic Development (with regard to Boarding Permits). There are also likely to be implications with regard to your home insurance policy and mortgage terms, which should be checked.