You have a couple of choices.
1) Use CenturyBreak setting in DBSControl. This is a system-wide setting and therefore will affect all such processes. you will also need to change the value each year.
2) Do it in your code. Load this field into a DATE column as part of the load process and then use logic to determine if the 'year' needs to be changed.
stage#1; load into a T!. The column in question is defined as DATE. The CenturyBreak setting will be used during the load process.
stage#2: move data from T! into T2 including folowing code
(CASE WHEN date-column >= DATE THEN ADD_MONTHS(date-column,-100 * 12) ELSE date-column END) AS new-date-column