You absolutely have to track this stuff. Otherwise you have no idea if you're doing a good job or where your money is going.
So I've used a few different models throughout my career. One is the relatively easy: there's an IT budget and everything goes in there. The second is the one I've got now, where there are 20 IT budgets for the 20 programs we offer.
In both cases, I've always tried to track which department was getting the money. It makes it much easier to see where your money is going and who is making the most demands on IT.
For hardware, we track everything in Asset Panda, and track asset tag, serial number, purchase date, and who it was purchased for.
For squishier things that everyone uses like Internet Access, we usually divide it up by department size and every employee counts as a "share". Phone service may either be cut up amongst different departments per line, though some businesses also like to track Long Distance charges for each department.
With a single IT budget, it is easier with hardware. You can move a laptop or a desktop where it needs to go, whereas if, say, marketing bought a laptop with their funds they become pretty grumpy if you try to give it to someone in finance.
Very helpful and timely post as my organization's fiscal year starts July 1st and I am going through this process right now.
Thank you all for sharing your knowledge.Robert