I use temporal ordering for all paper financial papers I receive. I used to sort into folders by category, but the took too long. At tax time, I do a linear probe for the date range of the tax year.

Since Apple started providing better end to end encryption for Notes and iCloud, my wife and I just use that. We also have a ton of storage on OneDrive, so periodically I ZIP up important stuff, encrypt it and put on OneDrive.