If you’ve been waiting to move your Membership Rewards points to your Delta SkyMiles account, your wait is over. For a limited time, American Express and Delta are offering a 15-percent bonus for all transfers — just in time for summer vacation.

American Express Membership Rewards members who convert their points into SkyMiles before July 15 will receive a 15-percent bonus.

The process involved is relatively straightforward. To be eligible for the bonus, members must first register for the promotion at http://www.delta.com/amexbonus.

Once registered, go to http://www.americanexpress.com/rewards or call (800) 297-3276 to complete the transfer. A one time 15-percent bonus will be applied to any Membership Rewards points transferred during the promotional period.

This promotion is limited to residents of the United States and members should expect to receive their bonus miles 6-8 weeks after July 15.

This bonus promotion will look familiar to longtime Membership Rewards and SkyMiles members, as AmEx and Delta have run similar promotions in the past.