Growing up as a Presbyterian, I was taught that Tithing is 10% of ourselves, not solely income. When we gave our time, our talents, our knowledge, our love, etc. it was all considered tithing. We were not required to pay 10% of our entire income as the lds church requires.
And this shall be the beginning of the tithing of my people. And after that, those who have thus been tithed shall pay one-tenth of all their interest annually; and this shall be a standing law unto them forever, for my holy priesthood, saith the Lord.
The following link is from For the Strength of Youth, a small booklet given to all youth of the lds church.
The Guide to the Scriptures
A tenth part of a person's annual increase given to the Lord through the Church. Tithing funds are used to build churches and temples, to sustain missionary work, and to build the kingdom of God on earth.
He that is tithed shall not be burned at his coming, D&C 64:23 (D&C 85:3)
Behold, now it is called today until the coming of the Son of Man, and verily it is a day of sacrifice, and a day for the tithing of my people; for he that is tithed shall not be burned at his coming.
It is contrary to the will and commandment of God that those who receive not their inheritance by consecration, agreeable to his law, which he has given, that he may tithe his people, to prepare them against the day of vengeance and burning, should have their names enrolled with the people of God.
The Lord's house will be built by the tithing of his people, D&C 97:11-12
Yea, let it be built speedily, by the tithing of my people. Behold, this is the tithing and the sacrifice which I, the Lord, require at their hands, that there may be a house built unto me for the salvation of Zion-
Tithing shall be disposed of by a council, D&C 120
Verily, thus saith the Lord, the time is now come, that it shall be disposed of by a council, composed of the First Presidency of my Church, and of the bishop and his council, and by my high council; and by mine own voice unto them, saith the Lord. Even so. Amen.
Talk from October 2002 General Conference -- Tithing: A Test of Faith with Eternal Blessings, Robert D. Hales
Not one ounce of my being believes that a person who does not tithe 10% of their income will be burned at His coming. I also do not believe God would deny Heaven to someone who has not tithed 10% of their entire income during their lifetime.
My unanswered question was:
Why would I pay tithing first, even when I don't have enough money to meet my other needs?
I was initially devastated when I received this answer that tithing should not be my first sacrifice, yet overjoyed to find the truth that I should sacrifice myself first and foremost. By taking care of my family, God will take care of us even more! My first priority as a mother is to take care of my husband and children. God does not need 10% of my "income." He needs 100% of ME!