Hey Aspirant !
Since you haven't mentioned whether you require the details of any specific category or not, I suppose you are from UR.
As per the the 2018 stats, under AIQ, 541was the last score through which a candidate got a Govt. medical College in Bihar and for the same seat under 85% State Quota, the cutoff was 533.
You can clearly see that the difference isn't much.
But this year, owing to various factors, there might be a chance of increase in cutoff following which,
It's advised to score a minimum of 555+ to be on the safe side.

You can go through the below mentioned link to have a better idea :

https://www.google.com/amp/s/medicine.careers360.com/articles/neet-cutoff-bihar/amp

Hope this helps.

All the Best !