There are two main reasons why your business has been put on anon-domestic energy deemed rate contract.
The most common reason is that your business has recently moved to a new address and has not yet contacted any electricity suppliers to negotiate a contract. Therefore, the same supplier that the old occupant used has begun charging you a deemed rate for any energy consumption.
Another cause is that your current contract has ended and, instead of termination or finding a new deal, your supplier has automatically rolled over to a deemed tariff.