Originally Posted by MSPeconomist

Is this the welcome bonus for a *new* DL AmEx card or not?

If you're talking about the annual threshold MQM bonuses (10,000 MQMs for $25,000 and $50,000 on DL Plat card and 15,000 MQMs for $30,000 and $60,000 spend on the reserve card, to be changed somewhat in 2020), please don't worry as spend that POSTS TO YOUR CREDIT CARD during the calendar year (regardless of your billing cycle and regardless of when you pay providing that your AmEx accounts remain in good standing) will lead to MQMs that count for that calendar year, 2019 in your case. For such MQMs, DL backdates them to the calendar year in which the spend threshold was reached regardless of when they actually hit your FF account.

The question here concerns the initial welcome bonus offers that the Plat and Reserve card generally carry for new and upgraded accounts, typically something like 5,000 MQMs for perhaps $3000-$10,000 spend during the first several months. For *these* MQMs, there's a question of whether spend depends on the calendar year or one's own billing cycle for the purpose of determining whether the WELCOME BONUS MQMS (and only these welcome bonus one time MQMs) will count as having been earning in 2019 or 2020.