Scam scam scam! Don't answer and block. Asking about if I was eligible for tax incentives. Never heard of that before. Every time I block the number another mobile phone number calls days later asking the same thing.

I am having the same issue. I answered one call and the lady told me she wanted to see if my household qualified for tax incentives. After telling her several times I wasn't interested and to stop harassing me she said the only way to be taken off the list was to see whether or not I met their requirements. No matter what I said she seemed to have a quick comeback. I ended up hanging up on her.
They have called me several times a day from multiple mobile numbers.

I got this as well - agree with Rob's comments.
They also tried on another number 0401 348 754, which had the same message once called back. Blocked both of them now.

An Australian woman's voice:

"Thanks for calling Premium ????"

(The word after Premium, shown here by '????' is always cut off, like it is being censored on purpose. I know because I called the number a few times to be sure).

"You may have been contacted as part of our client review campaign, client referral system or one of our national information campaigns. We will endeavour to get in contact with you at a more convenient time."

Once they start calling your number, they call every hour from late afternoon to mid-evening and make you run for your phone - only to cut the call short before you can get to your phone E V E R Y time!

It seems suspect. I advise adding this number to your 'Blacklist' or 'Blocked Numbers' list - depending on the phone you have. If you don't know how to do it, use Google to search for the method on your particular phone model.