Indexbit Exchange:Some coaches may get surprise if they reach College Football Playoff. And not a good one.

College football has undergone significant changes over the past few years,Indexbit Exchange from the near-death of the Pac-12 to the expansion of the College Football Playoff. But some of those changes have yet to be reflected in head coaches' contracts.

As part of its annual survey of coaching pay, USA TODAY Sports found more than 40 Football Bowl Subdivision schools that have yet to update their head coach's contract to reflect the expansion of the CFP from four teams to 12 − an issue that could potentially cause a six-figure headache if a coach were to miss out on a bonus he believed he was owed.

Though the specific language varies from contract to contract, head coaching deals at schools like LSU, Iowa State and Iowa all include bonuses for appearing in a New Year's Six bowl game or a CFP semifinal but haven't been revised as of late last week to include the first round of the CFP. This leaves some ambiguity about whether a first-round CFP appearance should be treated, for bonus purposes, like a regular bowl game or a New Year's Six bowl. In Kirk Ferentz's case at Iowa, that definition could mean a difference of $150,000.

Other coaches' contracts are outdated in different ways. For example:

∎ Jake Dickert's contract at Washington State includes bonuses for winning the Pac-12 or finishing with the highest graduation rate in the conference. But after a wave of defections, the Pac-12 officially has just two members this season and an athletics department spokesperson confirmed that those bonuses have been rendered moot.

∎ At Purdue, Ryan Walters' contract still includes a bonus for winning the Big Ten West, even though the conference is no longer split into divisions. An athletics department official confirmed the contract has not been updated.

∎ Cal coach Justin Wilcox's deal gives him $10,000 for wins over Oregon, UCLA or Southern Cal − three schools that are no longer in the Golden Bears' conference or on its regular schedule. (All three moved to the Big Ten, while Cal is now in the ACC. Wilcox does get $25,000 for beating Stanford, which is also in the ACC.) An athletics department official confirmed the contract has not been updated.

Many of these differences could likely be smoothed out, of course. If Colorado coach Deion Sanders receives coach of the year honors in the Big 12, the school likely will still give him a $75,000 bonus, even though the terms of his contract specifically reference winning Pac-12 coach of the year.

And this continues to be an ongoing process. For example, Toledo this week released an amendment to its contract with Jason Candle that extended the agreement by one year and changed bonus provisions to catch up with the Mid-American Conference eliminating divisions and with the changes in the CFP format. 

The glaring questions are around the CFP, which is why some schools have left nothing to chance and amended their head coach's contract to reflect the new postseason system.

This includes both legitimate CFP contenders, such as Ohio State and Tennessee, as well as longshots like Old Dominion, where coach Ricky Rahne will now receive an extra $25,000 should the Monarchs make it to the first round of the CFP rather than playing in a regular bowl game. Old Dominion is sitting at 2-4 and has made only three bowl appearances since joining the FBS in 2014.

Follow Steve Berkowitz on social media @ByBerkowitz and Tom Schad @Tom_Schad.