Irregular Verbs, Demystified
Irish only has a handful of irregular verbs, so breathe a sigh of relief. Unfortunately, as with most languages, the most commonly used verbs are irregular. So the sooner you face them, the better.

If you look up the irregular verbs in your foclóir, you may see a big conjugation table and assume you'll have to memorise the whole thing. Wrong! It's really much easier than that. It will help if you remember this guiding principle, which may not be obvious to the beginner:

There are a few exceptions, of course.

One very good way to learn these verbs is simply to read this list of questions and answers, out loud, once a day for a week or two. After that, you will find that you know most of them without having made an effort to memorise. Then you can focus on the particular ones that give you trouble.

abair (say)

present   An ndéir tú?        Deirim/Ní deirim
past      An ndúirt tú?       Dúírt/Ní dúirt
future    An ndéarfaidh tú?   Déarfaidh/Ní dhéarfaidh

beir (catch, give birth to)

present   An mbeireann tú?    Beirim/Ní bheirim
past      Ar rug tú?          Rug/Níor rug
future    An mbéarfaidh tú?   Béarfaidh/Ní bhéarfaidh

clois (hear)

present   An gcloiseann tú?   Cloisim/Ní chloisim
past      Ar chuala tú?       Chuala/Níor chuala
future    An gcloisfidh tú?   Cloisfidh/Ní chloisfidh

déan (make, do)

present   An ndéanann tú?     Déanaim/Ní dhéanaim
past      An ndearna tú?      Rinne/Ní dhearna
future    An ndéanfaidh tú?   Déanfaidh/Ní dhéanfaidh

faigh (get)

present   An bhfaigheann tú?  Faighim/Ní fhaighim
past      An bhfuair tú?      Fuair/Ní bhfuair
future    An bhfaighfaidh tú? Gheobhaidh/Ní bhfaighidh

feic (see)

present   An bhfeiceann tú?   Feicim (Chím in Ulster)/Ní fheicim
past      An bhfaca tú?       Chonaic/Ní fhaca
future    An bhfeicfidh tú?   Feicfidh (Chífidh in Ulster)/Ní fheicfidh

ith (eat)

present   An itheann tú?      Ithim /Ní ithim
past      Ar ith tú?          D'ith/Níor ith
future    An íosfaidh tú?     Íosfaidh/Ní íosfaidh

tabhair (give)

present   An dtugann tú?      Tugaim /Ní thugaim
past      Ar thug tú?         Thug/Níor thug
future    An dtabharfaidh tú? Tabharfaidh/Ní thabharfaidh

tar (come)

present   An dtagann tú?      Tagaim /Ní thagaim
past      Ar tháinig tú?      Tháinig/Níor tháinig
future    An dtiocfaidh tú?   Tiocfaidh/Ní thiocfaidh

téigh (go)

present   An dtéann tú?      Téim /Ní théim
past      An ndeachaigh tú?  Chuaigh/Ní dheachaigh
future    An rachfaidh tú?   Rachfaidh/Ní rachfaidh

(be)

present   An bhfuil tú?   Tá (or Táim)/Níl (or Nílim)
past      An raibh tú?    Bhí/Ní raibh
future    An mbeidh tú?   Beidh/Ní bheidh