As a small business owner you should be evaluating your expenses on a monthly basis.  This allows you to see where your money is being spent and can be a good indicator if you are spending too much money in one area.  Also reviewing your income and expenses on a monthly basis will show you as a small business owner whether you are making any money.  It also is a good idea on a quarterly basis so you can reallocate money somewhere else as needed.  If you evaluate once a year it is too late to see if you have made a profit or at a loss.