But MINDEF website says MUT is 3mths advance notice…....
ICT Notification
As an NSman, you may be called up for NS activities of not more
than 4 hours during the first 6 months after you completed
full-time NS. Every NS work year, you may be called up to a maximum
of 40 days of Operationally Ready National Service (ORNS). You may
also be called up for more than 40 days in one work year. However,
you and your employer must first agree to the extended service and
sign an undertaking to indicate your acceptance of the
arrangement.
The duration of your call-up may be shorter than 7 days [low-key
(LK) training] or 7 days and longer [high-key(HK) training].
Before your NS training begins, an advance notification will be
sent to you as follows:
a. 6 months in advance for HK training (i.e. 7 days and
longer)
b. 3 months in advance for Make-Up training (MUT) as well as LK
training (i.e between 2 to 6 days)
c. 2 months in advance for call-up activities of 1 day or
less
Such advance notification is given before every call-up to
minimise disruption and inconvenience
to your schedule.
If you do not attend your scheduled NS training, you will be
tagged as being Absent Without Official Leave (AWOL) from your
place of duty and subject to disciplinary action.