Consider a Negative Quality something that comes up, and in severity of consequence, in direct proportion to the amount of Karma you got for it. 25 points? You'll be bumping into minor and major issues that test your loyalty to the corporation (if you're still loyal
and they know that) very likely every run. Or you might have to fight off a kill team (if they think you've gone rogue) every three or four runs. Or you might have to scramble to cover up your link to the corp with a pretty severe frequency.
In
Pananagutan, Suki has a Corporate SIN at both stages. In the 2050's era, she hasn't been able to get her Shiawase SIN burned yet, so she's still on the run, and would be dodging a hitman or two every few runs. By the 'present day' part of the game, she's worked long and hard to get a very high reputation for both getting things done and keeping it quiet while she does, and strove to attract the attention of a specific individual so she could be
her 'company man', not one of a pool working for the company (EVO as well, in fact). Nonetheless, she's got a Corporate SIN, which she keeps quiet, and if I keep writing it past the current story (yeah, still working on the next part) she'll have to manage the demands of loyalty to the corporation with the necessities of what's functionally a cover identity, all while still keeping most people in the dark about who she actually works for.
Make sure you have the background concept laid out as clear as you possibly can, then talk with your GM about whether Corporate SIN will be appropriate - and how he might think about bringing its issues into play.
As soon as this person slips up in any way with regards to leaving behind biometric data - bam. Knight Errant (or more likely corporate goons) knocking on their door, roughing up contacts, etc.
It's hard to recover from something like that, so it encourages a healthy paranoia and a careful approach to things. In fact, other runners might wonder why you're so paranoid, as you're too paranoid for their tastes. And that's saying something, I think.
This is one way for the GM to go about it. On the other hand, depending on who you are and what you do inside the corporation, I can see a certain amount of that information being restricted, or resulting in a 'no such information found'. This, of course, presumes that you have some value to the corp ...