Anniversary Event Formula required to return hire date for 1st year and specific calendar date after

We've prepared an Anniversary Event Formula, our requirement is to return the hire date for the first year so that giving the employee's first accrual at the date of hire, and then continue to give the accuals for following years at 1st of January. The formula we have created does not accomplish that. So we wonder if the system is totally unable to give the such a dynamic anniversary date.

Formula;

DEFAULT FOR PER_PERSON_ENTERPRISE_HIRE_DATE IS '4712/12/31 00:00:00' (DATE)

effdate = get_context(effective_date, '0001/01/01 00:00:00'(date))

L_HIRE_YEAR = TO_NUMBER(TO_CHAR(PER_PERSON_ENTERPRISE_HIRE_DATE ,'YYYY'))