Be very careful when calculating the last date for doing something pursuant to a legal document.

If something has to be done “not later than the end of the period of six weeks starting with the relevant date”, then the last possible day for doing it would be the 42nd day of that six week period, with the “relevant date” being the 1st day of the period.

Example: if the relevant date is 1st May, the last date would be 11th June.

However, if it has to be done “within six weeks from the relevant date” the 1st day of the six week period is the day after the “relevant date” and the last date the 42nd day after it.

Example: if the relevant date is 1st May, the last date would be 12th June.

This is applicable in all legal documents, including legislation unless the document expressly indicates otherwise.

In a recent case it was decided that where the wording in a new Act of Parliament was “not later than the end of the period of six weeks starting with the relevant date” the last possible date for taking action (using the above examples) was 11th June, even though in the previous version of the statute the wording had been “within six weeks from the relevant date”, which would have made the last possible date 12th June.

The Court of Appeal held that there was no basis for presuming that, in using different language, Parliament intended it to mean the same!

A more familiar context where this applies is in relation to the period of a lease: if a lease is for a term of 10 years “from”, say, 1st June, the first day of the term is 2nd June and the last day is the 1st June 10 years later. If, however, the term is “from and including” 1st June, the last day would be 31st May 10 years later.

Getting the date right can become critically important when serving notices to end a contract or lease or to take up some advantage provided by a document, and we would therefore recommend that, as always, you take professional legal advice in good time.