voluntary contributions for future years

Hello Asking this for my son. He is working and has 7 years of NI contribution remaining required to meet the amount needed for a full pension. If he chooses to retire from his regular employed job and claim his work scheme pension earlier than the 7 years I would like to check 1) Can he make voluntary contributions from the time he retires early, onwards, until he pays enough for the 7 years? 2) Could he make voluntary contributions now to pay in advance for the 7 years, before he retires early? many thanks

Hi n99,
If your son is not employed or self-employed in the UK then he may pay the voluntary Class 3 contributions to maintain his State Pension entitlement.  Before deciding whether to pay voluntary contributions I would recommend him applying for a State Pension Forecast to check his current and future entitlement.  
He may do this via Check your State Pension forecast.
It is not possible to pay future tax years in advance.
Thank you.