I am an econ nerd

Today I had to pay a $20 deposit for my key to my PA office. I share this office with probably 10 or more people. I had my choice of paying in cash or with a check and I chose to use a check for a very specific reason. By taking into account the discount rate of my $20 and assuming that I would get my deposit back I came to the conclusion that the never-to-be-cashed check holds a higher net present value than the $20 bill that would be returned in 8 months time. This is also why I oppose estimated taxes as someone who expects a full refund.