If your employer pays for your health insurance policy (either fully or partially), you can claim TRS back on the amount paid by your employer. TRS is 19% on Irish Life health policies. For instance, if your employer pays 100€ for your health insurance, but your total premium costs 170€, this means you're paying 70€ every month from your salary, and you can still get 19% of 100€ refunded by Revenue.
You can claim your tax relief by logging into myAccount, on Revenue's website.
Bear in mind you will need this information (which you can find on your summary page, on the Kota app):
the date the policy started
who is covered by the policy and their ages
a breakdown of the cost of the policy for each person
the amount paid by your employer.
You can claim this during the year, or, at the end of the year, and collect it as a lump sum. Find out more about this process here.