Gift card was purchased without tax
By default, you can use a gift card having the same price and value to pay for the tip/SSG amount on an invoice.
You can use a gift card having a different price and value only if the organization allows it to be redeemed for 'tips'. Learn about the Redemption Setting for Gift Cards with Different Price and Value
Gift card was purchased with a tax amount included in its sale
You cannot use such cards to pay for the tip/SSG amount on an invoice.
By default, they can only be used to pay for services and day packages. Learn about What items can be redeemed using a gift card that was sold with tax?