Dec. 31 is the last chance for longtime Delta Air Lines frequent flyers to make a decision for their leftover Medallion Qualification Miles (MQMs).

In case you missed it, MQM-earning based on distance flown was ended a year ago, when Delta changed its status program to one based entirely on spending, or Medallion Qualification Dollars (MQDs).

Now if you still have old surplus MQMs in your account, you can choose whether to convert them to SkyMiles (at a rate of two MQMs to a mile) or MQDs (at a rate of 10 MQMs to one MQD). You can also choose a combination of miles and MQDs. If you do nothing, all your MQMs will be automatically converted to MQDs.

A handy guide to the conversion is at delta.com/myskymiles/convertmqms.

Got all that? Happy NYE!