When does the 2015 free agency signing period begin?
At 4:00 p.m. ET on Tuesday, March 10.
What are the categories of free agency?
Players are either "restricted free agents" or "unrestricted free agents." A restricted free agent may be subject to a "qualifying offer." A restricted or unrestricted free agent may be designated by his prior club as its Franchise Player or Transition Player.
What is the time period for free agency signings this year?
For restricted free agents, from March 10 to April 24. For unrestricted free agents who have received the June 1 tender from their prior club, from March 10 to July 22 (or the first scheduled day of the first NFL training camp, whichever is later). For Franchise Players, from March 10 until the Tuesday following the 10th week of the regular season, Nov. 17. For Transition Players, from March 10 until July 22. If the above-listed players do not sign by Nov. 17, they must sit out the season.
What is the difference between a restricted free agent and an unrestricted free agent?
In the 2015 league year, players with three accrued seasons become restricted free agents when their contracts expire at the conclusion of the 2014 league year. Unrestricted free agents have completed four or more accrued seasons. An unrestricted free agent is free to sign with any club with no draft choice compensation owed to his old club.
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Curious about the free agency options on the defensive line? Here's our rundown of the top linemen in this free agent class.

Lions defensive lineman Ndamukong Suh, unrestricted free agent

Giants defensive end Jason Pierre-Paul, unrestricted free agent

Broncos nose tackle Terrance Knighton, unrestricted free agent

Dolphins defensive tackle Jared Odrick, unrestricted free agent

Lions defensive tackle Nick Fairley, unrestricted free agent

Eagles defensive end Brandon Graham, unrestricted free agent

Panthers defensive end Greg Hardy, unrestricted free agent

Cardinals nose tackle Dan Williams, unrestricted free agent

Lions defensive tackle C.J. Mosley, unrestricted free agent

Bears defensive lineman Stephen Paea, unrestricted free agent

Eagles defensive lineman Cedric Thornton, unrestricted free agent

Colts defensive tackle Cory Redding, unrestricted free agent

Raiders defensive tackle Pat Sims, unrestricted free agent

Cardinals defensive lineman Tommy Kelly, unrestricted free agent

Cowboys defensive end Anthony Spencer, unrestricted free agent

Packers defensive lineman B.J. Raji, unrestricted free agent

Cowboys defensive tackle Henry Melton, unrestricted free agent

Lions defensive end George Johnson, unrestricted free agent

Browns nose tackle Ahtyba Rubin, unrestricted free agent

Buccaneers defensive end Adrian Clayborn, unrestricted free agent

Chiefs defensive tackle Kevin Vickerson, unrestricted free agent

Broncos defensive lineman Mitch Unrein, unrestricted free agent

Jets nose tackle Damon Harrison, restricted free agent

Dolphins defensive end Derrick Shelby, restricted free agent

Patriots nose tackle, Sealver Siliga, restricted free agent

Cardinals nose tackle Alameda Ta'amu, restricted free agent

Former Rams defensive tackle Kendall Langford, street free agent
What constitutes an "Accrued Season"?**
Six or more regular-season games on a club's active/inactive, reserved/injured or reserve/physically unable to perform lists.
What could restrict the ability of a restricted free agent to sign with a new club?
If he has received a "qualifying offer" (a salary tender predetermined by the Collective Bargaining Agreement between the league and its players) from his old club. He can negotiate with any club through April 24. If the restricted free agent signs an offer sheet with a new club, his old club can match the offer and retain him because the qualifying offer entitles it to a "right of first refusal" on any offer sheet the player signs. If the old club does not match the offer, it may receive draft choice compensation depending on the amount of its qualifying offer. If an offer sheet is not executed on or before April 24, the player's negotiating rights revert exclusively to his old club. In addition, a player who would otherwise be a restricted free agent may be designated by his old club as its Franchise Player or Transition Player. No restricted free agents were designated as Franchise or Transition players this year.
What determines an unrestricted free agent?
A player with four or more accrued seasons whose contract has expired. He is free to sign with any club, with no draft choice compensation owed to his old club, through July 22 (or the first scheduled day of the first NFL training camp, whichever is later). At that point, his negotiating rights revert exclusively to his old club if by June 1 the old club tendered the player a one-year contract for 110 percent of his prior year's salary. His old club then has until the Tuesday following the 10th week of the regular season (Nov. 17) to sign him. If he does not sign by that date, he must sit out the season. If no tender is offered by June 1, the player can be signed by any club at any time throughout the season.
What determines a Franchise Player?
The salary offer by a player's club determines what type of franchise player he is: exclusive or non-exclusive.
An "exclusive" Franchise Player – not free to sign with another club – is offered the greater of (i) the average of the top five salaries at the player's position for the current year as of the end of the restricted free agent signing period on April 24; or (ii) the amount of the required tender for a non-exclusive franchise player, as explained below.
Article 10, Section 2(a)(i) of the CBA sets forth the methodology, known as the "Cap Percentage Average," for calculating the required tender for such a player:
The Nonexclusive Franchise Tender shall be a one year NFL Player Contract for (A) the average of the five largest Prior Year Salaries for players at the position . . . at which the Franchise Player participated in the most plays during the prior league year, which average shall be calculated by: (1) summing the amounts of the Franchise Tags for players at that position for the five preceding league years; (2) dividing the resulting amount by the sum of the Salary Caps for the five preceding league years . . . ; and (3) multiplying the resulting percentage by the Salary Cap for the upcoming league year . . . (the "Cap Percentage Average") . . . ; or (B) 120% of his Prior Year Salary, whichever is greater . . . .
If a club extends a required tender to a "non-exclusive" Franchise Player pursuant to this section, the player shall be permitted to negotiate a player contract with any club, except that draft choice compensation of two first-round draft selections shall be made in the event he signs with a new club.
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Centers, guards and linemen â who might the Broncos sign in free agency? Here are the options for improving the line in free agency.

Chiefs center Rodney Hudson, unrestricted free agent

Broncos guard/tackle Orlando Franklin, unrestricted free agent

49ers guard Mike Iupati, unrestricted free agent

Packers offensive tackle Bryan Bulaga, unrestricted free agent

Raiders center Stefen Wisniewski, unrestricted free agent

Cowboys offensive tackle Doug Free, unrestricted free agent

Bengals guard Clint Boling, unrestricted free agent

Texans offensive tackle Derek Newton, unrestricted free agent

Dolphins center Samson Satele, unrestricted free agent

Broncos center Will Montgomery, unrestricted free agent

Cowboys offensive tackle Jermey Parnell, unrestricted free agent

Former Falcons guard Justin Blalock, street free agent

Bears center Brian De La Puente, unrestricted free agent

Vikings center/guard Joe Berger, unrestricted free agent

Rams offensive tackle Joe Barksdale, unrestricted free agent

Panthers offensive tackle Byron Bell, unrestricted free agent

Former Texans center/guard Chris Myers, street free agent

Lions center Dominic Raiola, unrestricted free agent

Bills offensive tackle Chris Hairston, unrestricted free agent

Seahawks guard James Carpenter, unrestricted free agent

Former Eagles guard Todd Herremans, street free agent

Chargers center Rich Ohrnberger, unrestricted free agent

Lions guard Rob Sims, unrestricted free agent

Bills guard/offensive tackle Erik Pears, unrestricted free agent

Former Titans offensive tackle Michael Oher, street free agent

Giants guard/offensive tackle Adam Snyder, unrestricted free agent

Former Giants center J.D. Walton, street free agent

Former Bengals guard Mike Pollak, street free agent
How many Franchise Players and Transition Players can a team designate each season?**
A club can designate one "Franchise" Player or one "Transition" Player among its potential restricted or unrestricted free agents.
Can a club decide to withdraw its Franchise or Transition designation on a player?
Yes. A club can withdraw its Franchise or Transition designation, and the player then automatically becomes an unrestricted free agent, either immediately or when his contract expires.
What is the salary cap for 2015?
The salary cap is $143,280,000 per club.
When must teams be in compliance with the salary cap?
At the start of the 2015 league year, which begins at 4:00 p.m. ET on March 10.
If a team is under the salary cap at the end of a given season, can the team "carry over" room to the next season?
Yes. A team may carry over room from one league year to the following league year by submitting notice to the NFL prior to 4:00 p.m. ET on the day before the team's final regular-season game, indicating the amount of room that the club wishes to carry over.
What is the maximum amount of room that a club can carry over?
100 percent of its remaining room.
Which tight ends in this year's free agency class might be fits for the Broncos? Leaf through the options in this gallery.

Broncos tight end Julius Thomas, unrestricted free agent

Dolphins tight end Charles Clay, unrestricted free agent (transition tag designee)

Browns tight end Jordan Cameron, unrestricted free agent

Ravens tight end Owen Daniels, unrestricted free agent

Broncos tight end Virgil Green, unrestricted free agent

Bengals tight end Jermaine Gresham, unrestricted free agent

Washington tight end Niles Paul, unrestricted free agent

Steelers tight end Matt Spaeth, unrestricted free agent

Falcons tight end Bear Pascoe, unrestricted free agent

Rams tight end Lance Kendricks, unrestricted free agent

Broncos tight end Jacob Tamme, unrestricted free agent

Former Eagles tight end James Casey, street free agent

Former Chiefs tight end Anthony Fasano, street free agent