The maximum number of people allowed attending private gatherings in Jersey will fall from 20 to 10 people from 02:00 GMT on Friday.
Health Minister Richard Renouf announced the change as one of eight measures intended to avoid a second lockdown.
Gatherings that require an organiser to carry out a risk assessment will also be cut from a maximum of 40 to 20 people.
The government said it would also be advising restaurants not to take table bookings of more than 10 people, unless they could provide a separate room or area for these guests.
The number of people allowed to attend funerals will also be reduced from 80 to 40 people.
Restrictions on the number of guests at outdoor events will not change, Deputy Renouf confirmed.
The change was originally announced as taking place on Wednesday, but this was later revised to Friday.