Tax code for employee has changed to 2957L

Hi, We have an employee who started in April on tax code 1257L but have since received a tax code change from HMRC to 2957L. The employee isn't that high paid so is not currently paying any tax. I wonder if you could tell me the possible reasons as to why the code has changed so drastically? Thank you.

Hi ,
 

A tax code is personal to an individual, therefore when the employer receives this they should operate the new code. If the emoloyee wants to know the reason for the change then they would contact personal tax. Personal tax will only deal with the individual. Thank you .