Bonjour Paul, Yes. Since "est" is the third person singular of être, you can use this expression in any tense by conjugating être accordingly.

Ça y était (t at the end, not s)

Ça y a été

Ça y sera

etc.

They're not pronounced quite the same. Ça y était = [sa je te] Ça a été = [sa a e te] On their own, the meaning is very similar - it was ok, it worked out. I'll ask Aurélie, who is a native speaker, to respond in detail.

Bonjour Paul ! Though you can technically conjugate this expression in past tenses (thanks Laura !), you will never really use it in other contexts than the present. Indeed, "ça y est" expresses some kind of immediate relief after an action been completed, hence its strong link with the present. You could possibly encounter "ça y était" in indirect speech, when reported someone's words, but none of the other forms would be used by a native (including the future). I hope that's helpful! Aurélie

As for the nuance of meaning between "ça a été" and "ça y était", I must disagree, it's two different expressions, with different meanings and uses: - Like I said above, "ça y était", means either literally "it/this was there" or, just like "ça y est", it can mean "here it was/it was done/I was done" in a context of indirect speech. - "Ça a été" literally means "it's been/it was", and as a fixed expression is used to express "it's been ok/it was ok", like at the restaurant for example: Serveur: Ça a été ? (It's been fine? / How was it?) Client: Oui, très bien merci. I hope that's helpful! Bonne journée !