Amazon is about to raise the price of its Prime membership service for the first time ever in the US, bringing the cost up to $99 per year, $20 above where it's been for nearly a decade. The price change goes into effect on April 17th, and those signing up or renewing their service before then will still be able to pay the original, less-expensive price for a final year.

While Prime's offerings aren't changing alongside the price increase, Amazon is citing Prime's increasingly substantial offerings as reason for the jump. It notes that there are now more items eligible for free shipping under Prime and points to Amazon Instant Video, access to which is now included in all Prime subscriptions. Amazon is also reported to be working on a music streaming service, which could ultimately be bundled with Prime as well.

Prime's student rate will also rise, though only by $10, up to $49 per year. Amazon's chief financial officer warned that the company was considering raising the price of Prime between $20 and $40 earlier this year, at the time citing increased shipping costs as reason for the added expense. This is Amazon's second big price increase on a US shipping service in a matter of months: back in October, Amazon increased the minimum order needed for free shipping to $35, up from $25, where it had been at for over a decade. Amazon also raised the price on Prime in the UK and Germany earlier this year.