Answer:
Technically it is to be on the gross amount since it is honoring God with all that we earn. The government calculates taxes based on total earned, I have always felt God was more important than the government and by using the gross figure we are showing Him just that. If someone has difficulty doing this, I usually tell them to do the 10% of the net and use your “offerings” to add to the “tithe” so that in the long run you probably are giving on the gross. Tithes and offerings are different things, the first being 10% which is supposed to go to the place of worship and the “offerings” those giving above and beyond which go to help the needy, etc.
Which goes to the second part of your question…the offerings part is to go to those in need.
One last note…God looks at the heart…I have sometimes given a tithe check to someone in great need that I believed at that time it did more ministry (and ultimately led someone to the Lord) than giving where my money was going for building buildings rather than people. Pray about it, and ask Jesus where He wants His money to go. For a short time, the ministry might be to help someone in great need that your offerings alone could not do.
Matthew 25:34-40 Then shall the King say unto them on his right hand, Come, you blessed of my Father, inherit the kingdom prepared for you from the foundation of the world: For I was hungry, and you gave me food: I was thirsty, and you gave me drink: I was a stranger, and you took me in: Naked, and you clothed me: I was sick, and you visited me: I was in prison, and you came unto me. Then shall the righteous answer him, saying, Lord, when saw we you hungry, and fed you? or thirsty, and gave you drink? When saw we you a stranger, and took you in? or naked, and clothed you? Or when saw we you sick, or in prison, and came unto you? And the King shall answer and say unto them, Verily I say unto you, Since you have done it unto one of the least of these my brethren, you have done it unto me.
Be blessed,
Pastor Brad