How to handle "optional protection line items" and rebates in the calculator

Hi, I’ve watched the great 101 Calculator Video, but I’m still unclear one a couple of things.

1.How should I factor in “Optional” protection plans/services which the dealer is tying to the terms. Should those just get added onto the dealer selling price?
2. Are rebates considered a presale incentive (taxed or untaxed) or a post-sales incentive? I believe these are combination of Costco and the manufacturer, but it’s hard to tell since the quote I got just lumps them in by the estimated monthly cost and a range of amounts due at signing.

Thanks in advance for your help!

Subtract the cost from the dealer discount.

This also applies to how you evaluate a deal.

If there is $500 in garbage added on, you need $500 in additional discounts, because it’s all garbage until proven otherwise.

Depends on the state. They’re taxable in more states than they are not.