TTM02200 | Tonnage tax elections: When election takes effect?
From HM Revenue & Customs · Tonnage Tax Manual
General rule
The general rule is that an election first applies from the beginning of the accounting period in which it is made. This rule has effect for companies that previously qualified and are electing into tonnage tax during a further window of opportunity. It does not apply to companies that first become qualifying for tonnage tax.
FA00/SCH22/PARA12 provides for an election to take effect from the beginning of certain other accounting periods. Where this is subject to the agreement of HMRC, the election should explain why one of these alternative start dates is required. For instance, the group might be carrying out a reorganisation to prepare for tonnage tax, and would not wish the election to take effect until after this reorganisation was complete.
Exceptions
There are a number of exceptions to the general rule: