Kendra's first pay check for the soon-to-be-released sex tape is a massive $680,000, RadarOnline.com has learned exclusively.

The reality television star secured the secret payment from Vivid in addition to receiving up to 50 percent of sales, as RadarOnline.com was first to report.

PHOTOS: Sex Tape Celebs

Until now, Kendra’s upfront payment has been kept secret. But several sources with direct knowledge told RadarOnline.com that the former Girl Next Door will get her whopping check this week.

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