Jason Witten and the Dallas Cowboys have agreed upon a four-year extension through 2021 on Tuesday that maxes out at $29.6 million and does not include more guaranteed money.

Witten turns 35 in May and was entering the final season of his deal. Witten is set to make $7.4 million in base salary and count $12.262 million against the cap. The Cowboys can restructure Witten's contract and earn close to $4 million in cap space whenever they need it.

This is the fourth contract Witten has signed with the Cowboys since he was a third-round pick in 2003.