Calculation of period of residence in relation to application for Naturalisation.

Non-EEA nationals 
Periods of reckonable residence are those for which you had a permission to remain stamp in your passport.  Certain periods of residence in the State covered by a permission to remain are not reckonable if that permission was –  

• For the purposes of study (whether or not that study involved you being in employment during any of the period of study), or 
• While your claim for asylum was being examined.  

Gaps between stamps are periods of unlawful residence and are not reckonable.
Certain non-Irish nationals are exempted by law from the requirement to have permission to remain.

EEA nationals. 
All of the time that an EEA citizen has spent in the State is reckonable for naturalisation purposes.

You can use the Online Naturalisation Residency Calculator Tool  as a guide to whether you satisfy the naturalisation residency conditions before submitting an application.