Chose is the plain past tense and works on its own: "I chose the red one". Chosen is the past participle and never stands alone — it needs a form of have or be in front: "I have chosen the red one", "she was chosen for the panel". If there is no helper verb, use chose.
The core difference
Both refer to the past, but they occupy different slots in a sentence. Chose is a complete verb by itself. Chosen is a fragment that needs propping up by have, has, had, was, were, is, are, been or being.
How to use each
- Chose: "They chose a Tuesday." "I chose not to reply." "He chose Manchester over Leeds."
- Chosen: "They have chosen a Tuesday." "The winner had already been chosen." "You were chosen because of the interview."
The test that settles it
Look at the word immediately before the gap. If it is a form of have or be, write chosen. If nothing helping is there — just a subject like I, she, the committee — write chose.
A quicker version for anyone who trusts their ear: substitute a verb with an obvious participle, such as eat. If "I have eaten" sounds right, then "I have chosen" is right. If "I ate" fits, then "I chose" fits. The pattern is identical: eat/ate/eaten, choose/chose/chosen.
The memory trick
Chosen has an extra letter, so it needs an extra word. It cannot go out unaccompanied.
Chosen as an adjective
One legitimate case looks like an exception. Chosen also works as a plain adjective in front of a noun: "the chosen candidate", "your chosen date", "the chosen few". Here it is describing, not acting as the main verb, so no helper is required. Chose can never do this — "the chose candidate" is impossible.
The common mistake
By far the frequent error runs the other way: "I've chose the venue", "they had chose to leave". Some varieties of spoken English regularly flatten the participle onto the past form, and you will hear it often enough that it stops registering. In writing it is still treated as an error, and it is one that readers notice. If a form of have is anywhere in the verb phrase, the word you need ends in -en.
Passive sentences
Passive constructions always take the participle, because they are built on be: "the design was chosen by a public vote", "nominees are chosen each spring", "having been chosen, she got to work". If the subject is receiving the action rather than doing it, you will need chosen every time.
Frequently Asked Questions
Is it "I have chose" or "I have chosen"?
"I have chosen." After have, has or had, English uses the past participle, which for this verb is chosen. "I have chose" is widespread in speech but not accepted in writing.
Is it "she was chose" or "she was chosen"?
"She was chosen." Any sentence built on was, were, is or are is passive and takes chosen. Chose can only be the active past: "she chose the team."
Can chosen be used without have or was?
Yes, but only as an adjective in front of a noun: "the chosen route", "my chosen field". As a verb it always needs a helper.