I've just spent a few minutes going through all my company's technology expenses to figure out which ones are subject to the completely daft rental tax that Chicago has extended to cover computing services. The City theorizes that rental tax is payable whenever you pay to use a piece of equipment that belongs to someone else for a period of time. This makes a lot of sense when you go to Hertz, but less when you use Microsoft Azure.
My understanding of the tax and the City's might not be completely orthogonal, but here are some examples of things that I've flagged for my company.
Salesforce.com: This clearly falls within the tax ruling. You pay for an online service that runs on someone else's computers. This is exactly what the city was after when they extended the rental tax.
Microsoft Azure: The tax only seems to cover Azure Compute fees, and specifically exempts Storage charges. So how are database hours taxed, then? With Azure, you pay for Database compute and storage together. Clearly Azure Storage is exempt, though. So now we've got a recordkeeping burden that Microsoft can't help us with yet. Great.
LinkedIn Professional: This may be subject to the tax, if you interpret the tax very broadly. But a LinkedIn subscription isn't so much for the use of its computers (which is free), but for enhanced features of the product that seem more like consulting services than compute time. I think we'll see some litigation over services like this one.
JetBrains ReSharper software license: This does not seem subject to the tax, because we're only paying for a license to run the software on our own computers.
Basically, the City is trying to raise revenue any way it can, but they don't have the technical wherewithal to understand why the tax as constituted makes no sense. Some people in my company feel this makes Chicago unattractive to business, but that's true only if you don't count the difficulty getting talented people to move away from all the city has to offer. It's a frustrating new tax, though, and one the City probably wouldn't have to impose if the rest of the state would pay for its share of the services that Chicago provides to it.