Hello Dlmm324,
I hope your weekend is going well! I wanted to share a great article with you that goes over setting up your retainer account in QuickBooks Online.
Record a retainer or deposit
https://quickbooks.intuit.com/learn-support/en-ca/service-items/record-a-retainer-or-deposit/00/2620...I personally do not tax retainers until the income is officially business income. Once the income is officially business income and shown on an invoice, it is then you will see the proper tax breakdown. I hope this helps!
Kindest Regards,
Lourdes Fernandez