Can I use income from sources other than a job as proof of income?

Can I use income from sources other than a job as proof of income?

Can you give a little context.  What do you need proof of income to do?  Is it for a loan?

Eric

My tax/financial advisers always tell me to get the appropriate tax from from those I work for (I do a lot of contracting work for other bowhunting companies as proof (as well as for taxation)) I have many revenue streams and I make sure Im always square with the IRS as I dont want to invite their wrath after the fact.

From what I've seen, lenders will usually ask for several years' worth of tax returns to gauge income.