Ireland has sovereignty over its tax law to a certain extent. For VAT for example there is an EU minimum standard rate of 15% (with an option for a reduced rate).

One of the biggest loopholes is _finally_ expiring in 2020: https://en.wikipedia.org/wiki/Double_Irish_arrangement .

Something else Ireland is limited in is custom tax deals/rulings with individual companies. As an EU member state, one can not just decide to apply an individual tax base or tax rate reduction without basing this in reality, hence https://www.nytimes.com/2016/08/31/technology/apple-tax-eu-i... .