A significant deadline for the Seattle Seahawks passed this past Friday when Kam Chancellor's $6.8 million base salary for 2018 became fully guaranteed, making it all the more likely that the Pro Bowl strong safety will remain with Seattle for the time being even with his football future in doubt because of a neck injury.

With that one in the rearview mirror, here's a look at some upcoming dates and events on the NFL's offseason calendar that will or could be of importance to the Seahawks:

Feb. 13: The first day teams can sign players whose CFL contracts from 2017 have expired.

The Seahawks haven't been linked to any CFL players this offseason, but they've had a few notable finds from Canada in years past. Cornerback Brandon Browner became a founding member of the Legion of Boom and started for parts of three seasons in Seattle's secondary. Wide receiver Chris Matthews recovered the onside kick that helped the Seahawks beat the Green Bay Packers in the NFC title game in January 2015. He then became an unlikely star of Super Bowl XLIX with 109 receiving yards and a touchdown.

Feb. 20-March 6: The two-week window for teams to designate franchise or transition tag players.

The Seahawks have 16 players who are scheduled to become unrestricted free agents, most notably tight end Jimmy Graham, defensive tackle Sheldon Richardson and wide receiver Paul Richardson. Sheldon Richardson is the player among those three that Seattle might need the most, but the cost of the franchise tag for a defensive tackle -- projected to be around $14 million -- may be prohibitive considering his production and Seattle's cap constraints. Kicker Olindo Mare in 2010 was the last Seahawk to play on the franchise tag. If they use it this year, expect it to happen much closer to the end of that two-week window than the start.

Feb. 27-March 5: The NFL scouting combine.

There's a lot more that goes on at the combine than the top college prospects for the upcoming draft being put through the paces. Agents and NFL teams convene in Indianapolis for the week, making this a time when the framework for some free-agent deals tend to be put in place. Plus, coach Pete Carroll and general manager John Schneider have yet to speak with the media since the end of the season. Both typically hold news conferences in Indianapolis, which could mark their first public comments on the drastic overhaul of Seattle's coaching staff.

March 12-14: "The legal tampering period."

Teams are permitted to begin negotiations with certified agents of players who are set to become unrestricted free agents during what has become known as "the legal tampering period." This is essentially the start of free agency even though free-agent deals cannot be signed until 1 p.m. PT on March 14. This only applies to free agents from other teams, so the Seahawks could sign any of their own before then. That list also includes safety Bradley McDougald, tight end Luke Willson, cornerbacks Byron Maxwell and DeShawn Shead and quarterback Austin Davis.

March 14: The start of the new league year and the official start of free agency.

The Seahawks are currently projected to have only around $14 million in cap space. They could and likely will create more space by releasing some higher-priced veterans (cornerback Jeremy Lane is one obvious choice). They could also extend someone like left tackle Duane Brown, free safety Earl Thomas or linebacker K.J. Wright and thereby lower the player's 2018 cap number. But as it stands now, the Seahawks might not have the cap space to be much more than bargain shoppers in free agency, especially if they spend big to retain any of their own free agents.

March 14 is also an important deadline for restricted free agents and exclusive rights free agents. Teams must submit qualifying offers to their own RFAs (players with three accrued seasons) in order to retain right of first refusal/compensation and they must submit minimum-salary tenders to their ERFAs (players with fewer than three accrued seasons) in order to retain exclusive negotiating rights.

The NFL's trading window also opens on this date.

March 14-18: The window for Seattle to exercise or decline center Justin Britt's option bonus.

The three-year, $27 million extension Britt signed last summer includes a $5 million option bonus for the 2020 season. If it's picked up -- which is expected -- Britt receives a $5 million bonus right away and his contract runs through 2020. Declining the option would void the final season of Britt's deal, making him a free agent after 2019, and that $5 million would instead be added to Britt's 2018 base salary, bumping it from $2.75 million to $7.75 million.

March 18: Defensive lineman Michael Bennett's $3 million roster bonus is due.

That could make this something of a soft deadline to either trade or release Bennett if the Seahawks are so inclined. A trade would obviously be preferable to releasing him and getting nothing in return, but there's no guarantee there will be a market. By trading or releasing Bennett, Seattle would incur a little over $5.2 million in dead-money charges while saving the team just under $2.2 million against the 2018 cap. His situation is explained in greater detail here.

April 16: When teams with returning head coaches can start their offseason workout programs.

While several players usually get together outside of Seattle for group workouts, this will mark the first time in 2018 that the Seahawks will officially convene. This part of the offseason is technically voluntary -- players aren't contractually required to show up until mandatory minicamp in June -- but the attendance rate is usually such that it's notable when players decide to skip portions of it or the entire program. Bennett has tended to work out on his own in Hawaii in recent offseasons, for instance. If Thomas remains unsigned to an extension by this time and wants to make clear his displeasure over the situation, he might take this as an opportunity to send that message.

April 20: The deadline for restricted free agents to sign offer sheets.

Seattle has five RFAs: running backs Mike Davis and Thomas Rawls, nickelback Justin Coleman, defensive end Dion Jordan and safety/linebacker Dewey McDonald. Davis, Coleman and Jordan all filled significant roles for Seattle last season and are expected to be tendered with the intention of being brought back. The team could also sign any of them to multi-year deals if it wanted.

April 26-28: The NFL draft.

The Seahawks aren't projected to receive any compensatory picks and could have as few as seven selections in all. That includes the No. 19 overall pick and no second- or third-rounders, which Seattle gave up in the trades for Sheldon Richardson and Brown. As has been stated here and elsewhere numerous times, there's a good chance the Seahawks either trade back in the first round or out of it entirely in order to recoup more picks.

Teams can hold a three-day rookie minicamp on either of the first two weekends following the draft, so from March 4-7 or March 11-14.

Late May through mid June: Organized team activities and minicamp.

Teams can hold up to 10 OTA sessions; Seattle's have tended to run from late May through early June. Those are followed by a three-day mandatory minicamp, which is usually in the middle of June. These practices will offer the first glimpse at the 2018 team on the field together and could also provide an indication of how cornerback Richard Sherman is progressing from surgery to repair a torn Achilles. He recently said he could "probably be fully ready to go in minicamp" but that he may be held out until training camp to be safe.