In most places it's now 2016 and if you're a Timesheets MTS user you might be receiving an error message when trying to record a timesheet entry. The message probably says something like this:
No period is defined for this date.
Someone with Super User privileges must define a period covering this date
In 2015 Timesheets MTS automatically created a period that covered all of 2015 but now that we have seen in a new year a new period must be created to cover it. This is easily done by logging into Timesheets MTS as a super user and going to the Tools->Options->Periods menu and adding a new period to cover the new year. Or you could create several periods to cover the year and even create new periods to cover next year and the year after.
If you were wondering why Timesheets MTS has time periods then there's two reasons. The first, is to stop users entering timesheets entries into the future. The second is to stop them from changing (or adding) timesheet entries to previous periods (because they've been locked for accounting purposes).