[ptaipale]

Finland: the tax administration knows almost everything about your money already, income tax is withheld by employers in advance through a pay-as-you-earn system (and this has been on for decades).

Tax authorities would like to get direct access to see bank accounts, that's not on yet.

Filing a tax return is very easy. Usually you need to do nothing, but if you have some specific tax deductions - not much is eligible - then you can do it with a fairly simple Web interface, or leave an equally simple paper form.

[maxerickson]

Your first paragraph is largely true for the US (people running quite small businesses don't necessarily have to keep up with pay as you earn, but the limits are a few thousand dollars and then the correct thing is to make regular payments during the year).

[jarcane]

The difference is that US agencies don't actually use this information, likely because of privacy regulations and stop forth. The right hand rarely knows what the left is doing, unless law enforcement or homeland security get involved.

You can see this even more starkly in the difference between the two in regards to medical records. Or even just basic personal details. My Kela card mostly tells doctors all they need to know, and even my address changes seem to get around without my having to do anything about it.

It was a bit unsettling at first for an American, but the systems here are largely pretty efficient except where unemployment is concerned...