kitzur-dot-net:
I cheated a bit and I just googled “maaser kesofim”.(You can do the same). Although there is a ‘daas jochid’ that maintains that “maaser kesofim” is “my-do’oraisa”, the vast majority of Poskim say it is at best ‘mi-derabbonon”. Of course, “maaser oni” is “midoraysa”, (every third and sixth year) but this is different than our “maaser kesofin”.