Looks like Samsung have increased their trade-in bonus on the Galaxy S21 to $400 (it has varied between $200 and $500 in the past two months). The $200 discount code also now appears to be stackable again, and you can also stack the $50 newsletter sign up voucher.
Ask a live chat agent (https://chatbot.samsungcs-au.com/) for a $200 discount voucher.
Eg, trading in a Galaxy S20 512GB: https://files.ozbargain.com.au/upload/519/88614/samsung.png
Need a code? Giving away a code? Please use the
Code Request Megathread
Do not ask for (or sell) codes in the comment section of deals.
you have to pay back the trade-in amount if you don't send back the phone. It states this as part of the process of getting your trade-in code.