It's quite common to see Research Associate posts advertised with the following conditions: "If the PhD will be awarded shortly, the appointment will be made at the Research Assistant level until the PhD has been completed".

I have picked out two keywords in there, "awarded" and "completed". For someone who's had a successful viva, made corrections and handed in the final thesis, but NOT yet graduated, will they be employed as Research Assistant or Research Associate? Many thanks.

Assistant. You need to have had your PhD awarded at the exam board first (after thesis has been submitted and any corrections have been approved by examiners), after which your university sends an official letter confirming this. This is usually sufficient for most places, although some places might want the actual certificate, which you only get after graduation.

In my postdoc, I hadn't had my viva when I started so I was employed as an assistant and they didn't have a policy of increasing grade or salary after PhD completion either - I always resented them for that. [And for many other things, hence one of the many reasons I left].

Thanks TreeofLife for an elaborate answer.