If you believe that your spouse is hiding assets and he or she owns a business, your first step is to obtain a copy of the business’s income tax return.  Use IRS form 4506.  Your spouse must sign this form, but generally the court will compel the exeuction of this authorization.  There are a number of ways to hide money in a business setting, including, but not limited to: Paying a salary to friends or relatives
Delaying receipt or depositing of funds
Purchasing artwork, furniture or other valuable items in the name of the business to increase expense and depreciate write-offs
Inflating costsYou should generally hire an accountant to help you ascertain the true value of the business and the actual income paid to your spouse.