How accurate is the VRT calculator

From the UK or NI?

The latter is VRT only if in NI for the last 6+ months, former is VRT + Customs + Vat.

6 months thing you mention is wrong, it has to have been in since before January 2021

Not as of 1st May, rules changed.

Edit - See here. The 'reasonable amount of time' is new, and some saying 180 days is fine, some saying less. https://www.revenue.ie/en/vrt/registration-of-imported-used-vehicles/registering-vehicles-from-ni.aspx

Vehicles purchased after 30 April 2024 can be registered in the State without being subject to these additional requirements. These vehicles will still require proof of Customs Declaration or proof that the vehicle has been in private ownership in NI for a reasonable period of time.

that would make sense alright. Thanks for that

YA it's fine for dealers. They claim the vat and then charge vat on the sale so the only real change is the 10 percent duty they need to pay and that's not in all cases either so lots of uk stuff coming in but mostly of the hybrid variety for max profits.