NEW ORLEANS -- We have now reached the math portion of the New Orleans Saints' offseason.

For the fourth year in a row, the Saints will have to trim mega-millions off their salary cap by March. They are roughly $10 million over the projected 2016 cap of $150 million -- and that's before signing any free agents to help them get out of their 7-9 rut.

The good news is the Saints are used to this by now -- and, more importantly, they've planned ahead for it. There are multiple ways they can get under the cap and still leave enough room for some mid-level free-agent signings. (New Orleans' bigger problem in recent years has been spending poorly on such free agents.)

First, let's focus on the Saints' best and most important option for trimming millions in cap space -- extending quarterback Drew Brees' contract.

Tuesday, we'll dive into the other ways the Saints can carve out millions more.

How much Brees costs now: Brees has one year left on the five-year, $100 million contract he signed in 2012. And he is set to cost a whopping $30 million against the Saints' salary cap ($20 million in salary and bonuses due this year, plus $10 million in pro-rated cap costs from past signing bonuses).

That's the highest salary-cap figure for any player since at least 2002, according to ESPN Stats & Information research.

Assuming the Saints don't plan to trade or release Brees, and assuming he doesn't agree to a straight pay cut, then the only way to lower his cap number is to work out a contract extension with him. That way, New Orleans can spread out some of the cap cost into future years.

How does that work? Let's say, for example, the Saints sign Brees for three more years and $60 million. That would add up to a total of $90 million in cap costs over four years.

Depending on how the Saints and Brees agree to structure it, they could divide the cap costs into an even $22.5 million per year over the next four years. Or they could even get it as low as $16 million this year, with hits closer to $25 million in each of the next three years.

To accomplish that, the Saints would give Brees something like a $20 million signing bonus (which would count $5 million per year against the cap over the next four years), plus a low base salary in 2016.

What is Brees worth? The toughest part of a Brees extension will be deciding his future value, since he turns 37 this week. Staying pat at $20 million per year makes sense because Brees wouldn't exactly be taking a pay cut, but he also wouldn't be breaking the Saints' bank to max out his value.

If Brees hit the open market at age 38, he would probably fetch even more than $20 million per year (which now ranks as the ninth highest average salary among quarterbacks in the NFL, behind the likes of Eli Manning, Philip Rivers, Matt Ryan and Joe Flacco).

But there is also plenty of curiosity as to whether or not Brees might accept a "hometown discount" to help the team win in his twilight years. The New England Patriots' Tom Brady agreed to a three-year extension in 2013 that wound up totaling just $30 million in new money -- well below his market value.

But that is an extremely rare case. Also, Brees is represented by agent Tom Condon, who reps many of the league's top quarterbacks and probably isn't eager to help start a new trend.

What's the deadline? One possible deadline is Feb. 10, when $10.85 million of Brees' salary becomes fully guaranteed. But that's really only important if the Saints are thinking of releasing Brees, which seems extremely unlikely.

After that, the Saints would need to get an extension done by the start of free agency on March 9. That's the deadline for teams to get under the salary cap.

If the Saints don't extend Brees by then, they'll have to rely on other ways to carve out the $10 million-plus from their roster.