So, what makes a payroll system at this scale so difficult? On the face of it, there are salary employees and there are hourly employees. How many taxing bodies does Canada have? Federal, provincial, and municipal? Is that a few dozen or a few hundred? Is Canadian tax code crazy complicated that doesn't allow for a rules based system? I'm honestly curious as to how a "simple" payroll system can go so far off the rail…
$460 million over 10 years is $46 million a year, which is still a lot of money, but if you break it down it's not nearly so mystifying. If all the money is being spent by contractors, we could assume that the loaded labour rate of the contractors is about $200K per year. It's been more than a decade since I was in Canada, but I'm guessing this is not an outrageous rate. That breaks down to 230 people working on the project. In truth, the payroll system seems to have been operational for the last 2 years and the system employs 500 employees (it was supposed to replace 1200 employees, thus saving money, but there is no indication if those 1200 were, indeed, replaced). I'm guessing that the $460 million includes those 500 employees for at least 2 years and may also include capital costs to house them (the reporter may not be interested in depreciating capital assets in their report).
So it's hard to say exactly how many contractors worked on this, but it's probably safe to say that there were more than 100. A government project with more than 100 contractors == not possible to succeed in my experience. Just the communication issues alone would be insurmountable. As time wore on and pressure to put something into use grew, the mistakes would have piled up causing absolute mayhem.
Unfortunately this is an all too common occurrence. If you go to any meetup in Ottawa and talk to government contractors I'm sure there will be a couple wiping their brow and saying, "This is a stroke of luck because it will take some of the heat off our our project that is burning even more money".