The 6ft 2ins midfielder, who has won two caps for Holland, began his career at Feyenoord before departing in 2011.
He has scored 11 goals in 40 league games for Twente and featured in their run to the Europa League round of 16 last season when they were eliminated by Bundesliga side Schalke.
Should there be no hitches in the transfer, Fer will be eligible to feature in Everton’s FA Cup fifth round tie at Oldham Athletic next month.
And skipper Phil Neville admits Everton were fortunate to emerge from their fourth-round showdown at Bolton Wanderers on Saturday with a 2-1 victory.
“It was probably bordering on a little bit lucky in the end,” he said. “We set off really well and for the first 15 or 20 minutes we looked as though we'd found our rhythm.
“The goal came at the end of a period of total domination and I thought it was going to be a quite simple game to win.
“Then, obviously, we conceded a goal and after that Bolton put us under a lot of pressure and we didn't play well enough after that.
“It was a proper cup tie and sometimes in a cup tie you just need to make sure you're in the hat for the next round. And that's what we are.”
