Chad Johnson says Ja'Marr Chase's wallet is about to be a whole lot fatter ... telling TMZ Sports he's sure Cincinnati is going to give the wideout a new contract worth "north of" $40 million PER YEAR!!

Chase, of course, has been looking for a redone deal from the Bengals for a while ... but now that he's officially entering his final season before free agency, Johnson tells us a fat payday is near.

Ochocinco says if the Bengals had gotten it done before this past season, they could have paid him roughly $30-$35 million a season. But now, after he led the league in yards, catches and receiving touchdowns -- he's anticipating it'll be much more.

"They decide to wait, he wins a goddamn triple crown, and now you've got to pay double," he said. "Yesterday's price is not today's price."

For the Bengals' part, they seem to be resigned to giving Chase the big figure -- as director of player personnel Duke Tobin told media last month they fully anticipated making him "the No. 1 paid non-quarterback in the league" this year.

As for Chase's teammate, Tee Higgins, Johnson told us he's expecting some more zeroes on the young wideout's paychecks soon -- explaining he deserves a deal with no "hometown discounts" from here.

"I want him to get what's fair," the Cincy legend said. "You don't take hometown discounts on first contracts."

Unfortunately for the Bengals, Johnson said paying the receivers likely means they'll have to trade star pass-rusher Trey Hendrickson ... because "it'd be impossible" to make the numbers work.