Voting method

Guernsey, The Reform (Guernsey) Law, 1948 (last amended in 2020), accessed 13 October 2020

Postal voting by absent voters.
2. Notwithstanding any of the provisions of the principal Law, a person whose name is inscribed on the Electoral Roll and who is a person to whom this Part of this Law applies (hereinafter referred to as "an absent voter") may vote by post in accordance with the succeeding provisions of this Part of this Law at an election for the office of [[...] People' s Deputy] (hereinafter referred to as "an election"). [...]

Voting from Abroad: The International IDEA Handbook, page 20

“Guernsey (…) allows external voting only for a provisional stay abroad, and registration fore lections can only take place within the territory.”