Eligibility for service is largely based on age at date of arrival in Israel with other factors such as family status, medical and physical profile and profession being taken into consideration.
When a person spends more than 120 (not necessarily continuous) days in Israel during a 12 month period, the date at the start of those 120 days is considered their date of arrival. The age at that date would determine the length of required army service.
To reset the date of arrival, the person would need to leave Israel for 2 years (1 year if they were on a recognized program such as Masa Israel Journey
Women arriving before the age of 20 are required to serve in the army whilst those arriving after the age of 20 have no requirement, (other than those with Katina Chozeret status). Religious women can be exempted from the draft if they do not wish to serve.
The following table shows the requirements based on age, medical and physical profile and family status for men.
Different regulations apply for doctors and dentists.
The final decision lies with the IDF. Additional information is available on the IDF's website