Under the Reports menu in QuickBooks, there is a submenu called Company and Financial.  One of the first reports you will see is called the Profit and Loss Standard.  While this report is self-explanatory, most users do not understand the power of it.  When you first open it, you will find it opens to the current month.  There are settings at the top where you can set the time frame you want to look at.  I suggest you choose a longer period like a year to date or even a beginning date from a few years ago.  When you refresh the screen, it will have the data for the periods you choose.

Here’s where it gets interesting and the true value comes in to play.  If you really want to understand the trends in your business or are looking for inconsistencies, at the top of the screen there is a drop down for “columns”  I would suggest you change this to months or quarters.  Once the report refreshes, the view will be such that you can now start seeing trends in your revenue and expense items.  If you collapse the report(another option at the top of the report) you can see the information in summary form.  This view is perfect for spotting months where expenses are missing, out of whack, doubled up in one month(or quarter) and missing in the next, etc.  You can even review your gross margin by time period to see if there is something strange about how the cost of goods sold is being booked.  Under the modify window at the top, you can change the reporting type from Accrual to Cash or vice versa.  Another view that is powerful is changing the columns to customer:job.  If you have coded various expenses into customer:job regardless of whether they are reimbursed or not, you will see a P&L by the customer:job.  This can be very powerful especially in construction or other industries where direct costs are coded to customers religiously.