The Taoiseach says he can't promise Ireland's corporate tax rate will remain at 12.5 per cent.
Over 130 countries in the O-E-C-D have signed an agreement to have a worldwide rate of at least 15 per cent.
The deal's due to be finalised in about six weeks' time, and Ireland has so far refused to sign up.
But speaking to Bloomberg on a visit to the US, Micheál Martin didn't rule out joining the global agreement.