I understand that the obligation to give Maaser from our income is a sub-category of the overall commandment to give Tzedakah but consider the following question:
If I made a promise (Neder) to give Tzedakah every day. Can I take Maaser money that I have set aside and use that to fulfill my vow ? or do I have to give the Maaser money in the name (LeShem) Maaser and money from my post Maaser earnings to (LeShem) Tzedakah?