Kylie Jenner -- Getting Legally Wasted On 18th Bday … In Canada

Kylie Jenner's turning 18 on Aug. 10th … but a celebration in the States is problematic, so we've learned she's headed to Canada to get legally wasted!

Kylie’s throwing a rager at Beachclub Montreal. It's Canada’s answer to Ibiza … a mini party island with a beach, pool, A-list DJs and lots of booze.

Here's the best part ... Kylie's being paid to celebrate her own birthday, and paid well ... we're told between $100k and $200k, just for showing up.

The club's owner, Olivier Primeau, is pulling out all the stops. Kylie will be choppered in, landing on a luxury boat that will dock next to a table stocked with bubbly. She'll also celebrate with a $3k cake.

That's not all that's legal in Canada at 18. Happy birthday ... Tyga.