Isle of Man, ELECTIONS (KEYS AND LOCAL AUTHORITIES) ACT 2020, accessed 3 August 2021
84. Place and manner of voting [1995/13/25 and drafting]
(1) A person entitled to vote at a national election or a local election may do so —
(a) in person at the polling station allotted under election regulations;
(b) by proxy; or
(c) in advance by means of post, but only if the conditions set out in section 85 are met.
(2) A person entitled to vote at a national election or a local election may do so by proxy if the person —
(a) has a medical emergency or urgent business necessitating overseas travel; and
(b) has applied under section 86.
This is subject to subsection (3).
(3) Subsection (2) does not apply if the person has already voted in person or
in advance by means of post.
85. Advance votes [1995/13/26 and drafting]
(1) A person who is or will be entitled to vote at an election may apply to the deputy returning officer of —
(a) the appropriate constituency (in the case of a national election); or
(b) the appropriate district or ward (in the case of a local election),
to vote, by post, in advance of the election in accordance with this section (whether in his or her own capacity or as a proxy on behalf of an eligible elector who meets the requirements of section 84(2)). […]
See also Voting by post
“Voting by post is an easy and convenient way of voting if you are unable to visit your allotted polling station. It is also available to those who choose not to vote in person. Postal votes can be sent to addresses in the Isle of Man, UK and overseas. You must be 16 years old or over on polling day and registered on the electoral register in order to vote.”