Think it is only the Vehicle registration cert which has the form on the rear for signing by both seller and buyer. Other than that- NCT disk and tax disk if current. One thing to watch when selling- it is preferable to complete the formalities and send in the form your self- I know of a few instances where old cars were purchased ( usually low value) and the buyer never completed the paperwork or sent it into the tax office and parking fines/ speeding tickets targeted the original owner. Although of course if you are buying you will prefer to do it yourself too!
Thinking of selling privately myself for the first time so this thread is of interest (not trying to hijack). If the amount you are selling the car for is considerable say 10k how have people handled the transaction with the buyer where cash is not an option.
A. You should complete the Change of Ownership details on the rear of the Vehicle Licensing Cert giving details of the new owner; enter the date of sale; you both sign the form and then you should post it to the DOE, VRU in Shannon. The buyer will then receive their new VLC in about 10 days by post from Shannon. (Keep a copy just in case).
B. If you are buying a brand new car (i.e. never taxed before), the garage should give you an RF100 Form which you use to tax the car. Once the car has been taxed you will be sent the new VLC from Shannon. (If the car was taxed previously the garage should have the VLC which you and they should complete and they should post it to Shannon on your behalf.)
NB. Older cars generally had 2 documents a Vehicle Registration Cert & Log Book. This has been replaced by a single document - a 4 page, purple- coloured booklet.