An early election or not?

According to Nick Robinson, The Code for Fiscal Stability rules out the possibility of a March election:

The date of the Pre-Budget Report was announced today as 9th of December. The Code for Fiscal Stability, which Gordon Brown put into law in 1998, states that there must be "at least three months" between the Pre-Budget Report and the following Budget.

Thus, the earliest possible date for a 2010 Budget is the 9th of March. That is after the latest possible date - 1st of March - on which Gordon Brown could call a March election.

This is the relevant clause:

If, as is usual, there is only one Budget in a financial year, the Treasury shall publish a Pre-Budget Report (PBR) at least three months prior to it, unless this is the first Budget of the Parliament, in which case a PBR shall not be required.  In addition, if there is more than one Budget in any financial year, only one PBR shall be required.

What the clause doesn't say is if the Budget following the PBR has to be in the same Parliament.

So, it would seem that Brown does have the option to call an early election, which would take place before the previously announced tax rises kick in.