The Glasgow giants are set to give the England international a 10-day deadline to recover from a niggling knee injury before commiting to the deal.
"Perhaps we have endeavoured to push this transfer for a variety of reasons," chairman David Murray told the club's official website.
"But, taking all the relevant matters into consideration, including several past situations, I must be 100 percent satisfied of the player's ability to sign and make an impact in playing, which we believe will be the case.
"I appreciate Everton's co-operation in the matter."
If the expected transfer of Ball gets the green light from Ibrox chiefs the 21-year-old will become Rangers' second most expensive signing ever after £12 million man Tore Andre Flo.
