How can I extend my total stay in Ireland to five years for permanent residency if the master's program is only one year with two years post-study work visa?

It depends - a one-year master's plus a two-year post-study work visa (Stamp 1G) is not enough for five years of reckonable residence for permanent residency in Ireland, since study time mostly does not count.

To reach five years:
- Complete your 1-year master's and use the 2-year Stamp 1G post-study work visa.
- After Stamp 1G, secure a job and move to a work permit (Critical Skills Employment Permit or General Employment Permit).
- Time on a Critical Skills Employment Permit is the fastest route - after 21 months, you can apply for Stamp 4 (long-term residency).
- You need a total of 5 years on qualifying work permits (plus up to 12 months of study time) to apply for long-term residency.