The Washington Redskins will invest $25 million in offensive tackle Jon Jansen over the next six seasons but, according to NFL Players Association salary documents, fashioned the contract extension he signed Wednesday in a manner that makes his cap impact relatively palatable.

A four-year veteran who has started every game during his Redskins tenure, Jansen ended months of negotiations by agreeing to an extension that will keep the former University of Michigan star off the unrestricted free-agent market next spring and also makes him one of the league's highest paid right offensive tackles.

The new extension includes a $4 million signing bonus and an option/buyout bonus of $4 million due next spring. That essentially guarantees Jansen $8 million in guaranteed money, because the Redskins must pay the $4 million next spring to either exercise an option for the 2004-2008 seasons or to buy out the balance of the contract.

Base salaries for the extension are $600,000 (for 2003), $1.4 million (2004), $2 million (2005), $4 million (2006), $4.25 million (2007) and $4.75 million (2008). There are no reporting, roster or workout bonuses delineated in the NFLPA documents for the extension.

"It was a matter of wanting to stay here, to help this team achieve things we have talked about, and of getting the numbers right," said Jansen, who joined the Redskins as a second-round choice in the 1999 draft.

While the per-year average falls shy of the $5 million Jansen was seeking, the Redskins invested more in the signing and options bonuses. But the big advantage for the team, in addition to retaining a player who likely would have been among the most pursued free agents next spring, is in the fairly low cap figures for the first three seasons of the extension.

The cap numbers for those years -- $2.038 million in 2003, $2.638 million for 2004, and $3.238 million for 2005 -- are all livable. They are dwarfed, for instance, by the cap charges the Redskins face for Jansen's offensive left tackle partner, Chris Samuels.

Samuels' cap charge will jump about $5 million in 2003 from this year, and could be even higher than the scheduled $7.212 million if the team's 2000 first-round draft choice reaches some performance benchmarks this season. The Samuels contract tops out in 2006, its final year but also a voidable one, with a cap number of at least $9.676 million.

By comparison, Jansen's cap number for '06 is $5.238 million and does not exceed $6 million at any time in the deal.

Len Paquarelli is a senior writer for ESPN.com.