Disclaimer: Nothing of what I will say is official church doctrine, but is solely my opinion. The church uses tithing funds to build up the church and for humanitarian work, and these are noble causes worth contributing to. Faithful members of the church are couseled to tithe 10% of their income. There is some dispute whether that means 10% of gross or net income. My opinion is that it is net income. My reasoning for that is thus: the government takes their share of what you earn, then your involuntary retirement, health, dental, life insurance, union dues, flex account, etc., and then you get your money. I tithe 10% of what I get after everyone else sticks their hands in and takes what they want. Still, it hurts losing that much money, but I do it faithfully. The last time I attended the temple, I received an answer, a witness by the Holy Spirit, to a solemn and heartfelt prayer about tithing: that it is merely a similitude of the sacrifice Christ made to redeem our souls, and its purpose is to build up His church. The idea is that if you tithe faithfully, the Lord will ensure that you have enough to meet your needs. Note that needs doesn't mean wants! You need to provide for the means for you and your family to live, nothing more. I've heard people say that they get more out of the 90% than they'd get out of 100% (because they're scrimping and saving more). If you can't pay tithing this month because bills are greater than 90% of your income (this is really high...maybe you need to get rid of some bills?), you can always catch up as long as you catch up. As much as possible, live within (below) your means. When it comes down to it, it's the simple rule of math. If you don't pay your electric bill and pay tithing instead, you will be blessed, but you will be blessed in the dark. Obeying commandments faithfully, brings blessings. That is a fact!