'Grey's Anatomy' Star Kevin McKidd Agrees to Modified Spousal Support With Ex-Wife

"Grey's Anatomy" star Kevin McKidd will be shelling out a hefty monthly spousal support payment for his first wife, Jane ... but it looks like the cash cow's running dry sooner rather than later.

According to new legal docs, obtained by TMZ, Kevin -- who played Dr. Owen Hunt on the popular medical drama -- agreed to change the terms of his spousal support.

The docs say Kevin will pay $45K every month, but the payments will end no later than March 2027 … and Jane will be on her own after that.

Same goes with health insurance -- the actor will be paying $900 each month until no later than March 31, 2027 ... so come April 1, he's off the hook for that too.

However … he will have to cut her a fat check -- to the tune of $60,500 -- as a "buy-out of any further obligation" with respect to her medical insurance.