“I’ll Pass” Is a Polite Way to Decline

If someone asks, “Would you like some cake?” and you answer, “I’ll pass, thanks,” you mean “No thanks, not this time” — not “I will succeed”. Here, pass means choosing not to take the opportunity in front of you, so it can decline food, an activity or a suggestion.

It is a little softer than a bare “No”, though still brief and informal in everyday Australian conversation. If you are turning down an invitation and want to sound warmer, you can add: “I’ll pass tonight, but thanks for asking.” The meaning depends on context: in “I passed the exam”, pass still means succeed; in “Pass me the salt”, it means hand something to someone.

https://dictionary.cambridge.org/dictionary/english/pass
https://www.collinsdictionary.com/dictionary/english/pass