Unlike most of the world which uses the gregorian calendar, Saudi Arabia on the other hand goes by the Islamic or Hijri calendar for its official use. The islamic calendar can be a little bit confusing to follow when not accustomed to it. The islamic calendar is a lunar calendar having 12 lunar months in a year of about 354 days. Because this lunar year is about 11 days shorter than the solar year, Islamic holy days, although celebrated on fixed dates in their own calendar, usually shift 11 days earlier each successive solar year, such as a year of the Gregorian calendar. Islamic years are also called Hijra years because the first year was the year during which the Hijra occurred—Islamic prophet Muhammad‘s emigration from Mecca to Medina.
The Islamic or Hijri calendar does have 12 months the same as the gregorian calendar. These months are identified as:
1. Muharram محرّم (or Muḥarram al Ḥaram)
2. Safar صفر (or Ṣafar al Muzaffar)
3. Rabi’ al-awwal (Rabī’ I) ربيع الأول
4. Rabi’ al-thani (or Rabī’ al Thānī, or Rabī’ al-Akhir) (Rabī’ II) ربيع الآخر أو ربيع الثاني
5. Jumada al-awwal (Jumādā I) جمادى الاولى
6. Jumada al-thani (or Jumādā al-akhir) (Jumādā II) جمادى الآخر أو جمادى الثاني
7. Rajab رجب (or Rajab al Murajab)
8. Sha’aban شعبان (or Sha’abān al Moazam)
9. Ramadan رمضان (or Ramzān, long form: Ramaḍān al Mubarak)
10. Shawwal شوّال (or Shawwal al Mukarram)
11. Dhu al-Qi’dah ذو القعدة
12. Dhu al-Hijjah ذو الحجة
Now where the islamic calendar can become confusing is say for example, one looks at the sixth month, jumada al-thani. Because it is the sixth month one may mistakenly assume that it correlates to the sixth month of the gregorian calendar which is June. But because the islamic calendar is a lunar calendar where the days shift each year, the sixth month will actually rotate as well. It will always be the sixth month of the islamic calendar but unlike the gregorian, will not always fall at the same time or season of the year. To further explain, jumada al-thani may correlate with the gregorian month of June one year but several years later it may be Rabi al thani which correlates to the gregorian month of June.
Problems have occurred with conversion from hijri to islamic dates particularly when it comes to official documents such as passports, visas, national identity cards, marriage licenses, drivers licenses and other documents too. For example a Saudi travels outside of the Kingdom as a student and needs to obtain a local drivers license or wishes to apply for a credit card. If he or she is in the western world, the application must be completed in the host country language and most applications will require date of birth. This is where the Saudi will have to figure out the calculation from hijri to gregorian date. All official Saudi documents in the Arabic language naturally have the hijri date. It is not unusual for a Saudi to inadvertantly age oneself as either more advanced in years or younger in year due to miscalculations between hijri and gregorian dates. Or the year may have been converted correctly but the month or day will be incorrect. Most of the Saudis whom I have met and had the opportunity to check their identity cards or other documents which needed to be in English usually have a mistake made with the date whether it be the month, day or year.
One may not think this may pose a big problem but given how so much data is entered today in various databases, mistaken dates could also lead to problems with mistaken identity, particularly when taking into account how Saudi and other Arab names can be very common.
Note I included images of 2009 Gergorian Calendar vs Hijri Calendar to provide readers with a refernce for dates. The Hijri dates are the smaller font.