When you're a frequent flyer with Delta, you can earn elite "Medallion" status, entitling you to special benefits and perks like first-class upgrades and waived fees.To qualify for Medallion status, you need to earn a certain number of Medallion Qualification Miles, or MQMs, and Medallion Qualification DollarsMQDswithin a calendar year.MQMs are the total distance you've flown within the year, and MQDs are the total amount you've spent on base fares within that year.To get a boost on MQMs, you can open one of Delta's two premium credit cards and meet minimum spending requirements: the Platinum Delta SkyMiles Credit Card from American Express, or the Delta Reserve Credit Card from American Express.Read more personal finance coverage.Two of Delta's personal credit cards can earn you bonus Medallion Qualification Miles, or MQMs, when you meet spending requirements in a cardmember year.If you want to earn Delta Medallion elite status, MQMs are part of the requirements you'll need to meet in order to qualify, so leveraging your credit cards to help get you there can be a great strategy.The Platinum Delta SkyMiles Amex card is currently offering 75,000 Delta SkyMiles and 5,000 MQMs when you spend $3,000 in the first three months. Plus, you can get a $100 statement credit when you make a Delta purchase in the first three months. You can also earn MQMs for meeting annual spending thresholds on the cardkeep reading for more info.The Delta Reserve Amex card is now offering 75,000 Delta SkyMiles and 10,000 MQMs, after you spend $5,000 in the first three months. The card has a high annual fee of $450, but offers a few additional benefits, and like with the Platinum Delta Amex you can earn additional MQMs for meeting annual spending thresholds.Both of these welcome bonus are only available until October 30, so don't wait long to apply.What are MQMs, and how are they different from SkyMiles'When you join an airline's frequent flyer program, you earn miles virtually every time you fly. Specifically, these miles areredeemable milesones that you can redeem for flights, upgrades, or more. Delta calls these "SkyMiles," which is also the name of the frequent flyer program.Redeemable SkyMilesRedeemable miles are typically awarded as a function of how much you paid for the base fare on your ticketon some partner flights, they're awarded as a function of fare class and distance flown. For example, Delta SkyMiles members without elite status earn 5 redeemable miles per dollar spent on a flight's base fare.MQMs for Delta elite statusWhen you fly fairly frequently, you can qualify for elite status within the program. Elite status is usually a tiered system, and each tier offers a few additional perks, like bonus mileage earning on flights, upgrades, priority boarding, a dedicated phone support line, and waived fees. Higher tiers come with better benefits, naturally.In order to qualify for elite status with an airline, you'll typically need to meet certain qualification requirements. Delta, typical of US airlines in 2019, requires you to both fly a certain number of miles or a certain number of flights, and spend a certain amount of money on base fares throughout the previous calendar year to get elite "Medallion" status.Delta refers to the total number of miles you've flown in a year as Medallion Qualification Miles, or MQMs. You typically earn one MQM for every one mile you fly, although if you fly certain full-fare economy or business class fares, either with Delta or with a partner, you can get 1.52x MQMs per mile flown.(Keep in mind that "miles flown" is calculated as the official routing distanceif you fly a few extra miles to go around a storm, or land on a different runway, you won't earn extra MQMs.)The total amount you've spent on base fares is referred to as Medallion Qualification Dollars, or MQDs.While you'd normally need to meet both MQM and MQD requirements to hit the next status level, there are two exceptions.The first is an exception to MQMs: If you fly a lot, but just very short distances (think a weekly round-trip between New York and Washington, DC), you may be able to qualify by earning enough Medallion Qualifying Segments, or MQSs.Also, if you spend $25,000 or more on a Delta credit card during the qualification year, the MQD requirement will be waivedexcept for Diamond Medallion status, which requires spending $250,000 in a calendar year to waive the MQD requirement.That's why anyone who has or is chasing elite Medallion status with Delta should consider their MQMs when looking at the Delta credit cards. Two of the three main cardsthe Platinum and Delta Reserveoffer bonus MQMs when you open a new card. Remember that even if you've had one card before, you can still earn the bonus on the other.How Delta Amex cards help you earn MQMsIn addition to their welcome bonuses, the Platinum Delta Amex and Delta Reserve Amex offer MQMs for meeting spending thresholds each year.Platinum Delta AmexEarn 10,000 bonus miles and 10,000 MQMs after you spend $25,000 in a calendar yearEarn another 10,000 bonus miles and 10,000 MQMs after you spend $50,000 in a calendar yearDelta Reserve AmexEarn 15,000 bonus miles and 15,000 MQMs after you spend $30,000 in a calendar yearEarn another 15,000 bonus miles and 15,000 MQMs after you spend $60,000 in a calendar yearNote that starting in 2020, the Delta cards will no longer offer bonus miles alongside the MQMs for meeting these spending requirements. This is just one benefit update of many coming to Delta's co-branded Amex cards; other changes will include more bonus categories for earning miles on spending and, unfortunately, annual fee increases.One last thing to keep in mind: Each year that you hold Medallion status, you can roll over any MQMs above the requirements for your status level to the next year. So say that you earn 55,000 MQMs in a calendar year, and end up with Gold status, which only requires 50,000 MQMs. You'll roll over those extra 5,000 MQMs for the next qualification year.Click here to learn more about the Platinum Delta SkyMiles Credit Card from American Express.Click here to learn more about the Delta Reserve Credit Card from American Express.More credit card coverageWhat's the best airline credit card'The best cash-back credit cardsSouthwest credit card reviewBest rewards credit cardsJoin the conversation about this storyNOW WATCH: 7 lesser-known benefits of Amazon Prime Click here to read full news..