Hi Samantha, this is a very general question. It really depends on what are you comparing and if variance is adverse (actual result worse then expected – budgeted) or favourable.- actual result better then expected/budgeted.
Most of the reasons can be explained by common sense. If u need further help please leave a message.
There may be quite a few reasons as seagoat points out. Remember that a budget is more of an estimated assumption in regards to how the business may or is expected to perform if everything goes as planned. Normally the budget is even written up before any business activity even takes place. Its very likely that youre actual results won’t match budgeted ones.