Hi skyknyght,
I´m not 100% sure about the following calculations, hoping you´ll get a better/surer answer soon. But I guess I´m not totally off track...
- You´re allowed 90 days per calendar-half-year. Thus exit + re-entry does not reset anything.
- You have to wait until half-a-(calendar)-year passed since your first entry.
- Taking your example:
- If you enter Ireland on the 1st of March, you may stay any 90 days within half a year from that day onwards.
- Between 01st March 2012 (date of first entry) and 31st of August (= 6 calendar months from first entry) you may stay any 90 days.
- If you stay consecutively, you have to leave Ireland on or before 30th May 2012 (01 March + 90 days), and may not re-enter before 01st of September (date of first entry + 6 calendar months + 1 day).
- You may re-enter for a new period of 90 days after the initial 6 months are up or later.
I guess the two important things to know are:
- 6-month-periods counted as per 6-months in the calendar from date of first entry.
- 90 days are 90 days are 90 days...
So your 4 days + 3 months will be a close call. Just make sure it´s not more than 90 days altogether, or apply for a visa with the Irish Embassy before you go.
When leaving Ireland after only a few days, make sure to get some sort of exit-confirmation! In Ireland, passports are not routinely stamped upon departure! I do not know what counts as proof of departure? Boarding pass? Make sure to get sthg you can rely on!
If you want to really push things to the limit, make sure you do not arrive on a late-evening flight: Every calendar-day counts, thus if you arrive at 23h30 in the evening you lose that day, because it counts in full... I don´t know if lingering before passport-control until midnight helps - this would depend on when they change their stamps...
Oh yeah - and you never have "the right" to enter: On request you'll have to prove that you have enough money to support yourself without work OR prove that someone will pay for you AND that you have health insurance. Based on this the IO can take a decision whether to admit you or not. They never HAVE to admit anyone except their own citizens, EU citizens can only be rejected under very very very specific circumstances, everyone else can be rejected w/o reason...
Happy travels,
Regards,
Christian