Alex: There is no cost to receive credit for United flights taken up to 30 days prior to your MileagePlus enrollment date. You can receive credit for United flights taken 31 days to six months prior to enrollment for a fee. See this Web page for more information.

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Can I receive credit for trips taken before I had a MileagePlus account?

You may receive mileage credit for United-operated flights taken up to 30 days prior to your enrollment date free of charge. No mileage credit will be given for partner flights. You may also receive mileage credit for United-operated flights taken between 31 days and six months prior to enrollment for a $25 USD service fee. Please contact the MileagePlus Service Center or mail a copy of all ticket receipts and the original boarding passes from your United flight(s) to: MileagePlus Service Center, P.O. Box 6120, Rapid City, SD 57709-6120.

If the flights taken were more than 30 days prior to your enrollment, please be sure to include your MileagePlus account number and a telephone number along with a credit card number and expiration date. You may also pay by check or money order. Please make your check payable to United Airlines and include the information from one form of identification (driver’s license number, passport number, or military ID number). This information should be placed on the top left hand corner of the check. All missing mileage requests must be submitted within six months of flight date.