You may also want to see if adding an expense and getting a reduction in your refund could be due to the reduction or elimination of a credit that you qualify for without the expense being added. Credits like the Earned Income Credit or Premium Tax Credit can be responsible for a dramatic decrease of your refund.
Try entering an expense that is just big enough to create the refund fluctuation, calculate the difference between it the the higher refund, then examine your return for one or more credits that add up to that
difference.
