Originally Posted by
RealHJ
CZ has no or very low YQ surcharge.
Delta ECVs are usable to pay for such travel related fees/taxes, but not incidentals like baggage or seat upgrades.
Read the terms or your ECV exactly what it can and can't be used for.
Give the agent some 10-30 min to apply it towards your taxes though, as the internal systems are build not to allow that, so they need to escalate that and work through some workarounds to actually make it work how it should per the T&Cs (if the agent tells you no, point them to the T&Cs that say yes and ask them to escalate).
Although an agent may be able to apply an ECV to award ticket taxes, this cannot be done by the ECV's owner on an award he is booking thru Delta's website.