Standard mileage offer is 3 WorldPerks miles per dollar spent, however Northwest reserves the right to increase the mileage offer at its discretion. Miles earned on price of items purchased excluding any applicable taxes and shipping charges. All products, unless otherwise specified in individual offers, will earn miles according to the terms of the individual offer, with the exception of orders of and including American Express Gift Cheques. Miles awarded on purchases when shopping from the WorldPerks Mall to giftcertificates.com only. Miles are not earned on purchases directly from giftcertificates.com or any other branded site. Not valid with any other offers or promotions. WorldPerks miles will not be credited for merchandise returned to giftcertificates.com. Miles for most purchases will appear on the member's account 6 to 8 weeks from receipt of order. The transaction date listed in your WorldPerks account summary is based on the date of purchase. Transaction date is the date that your credit card is charged, which is the date the product is shipped. Participation in the WorldPerks program is subject to the terms and conditions of the WorldPerks Member's Guide.