Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
Unless he has committed a criminal offence there is no possibility of imprisonment. Imprisonment for debt ended in 1869 although it is possible to get banged up for up to six weeks where the debt arises from a court order. It is called a judgement Summons. Firstly, the court must be satisfied that the payer has, since the date of the order, had the means to pay the debt and secondly it must be satisfied that he has refused or neglected, or refuses or neglects, to pay the sum due [auth: Stowe Family Law LLP].
For assistance he should try National Debtline. The link is here:
MoneySavingExpert.com have good advice available also, have a look here:
I do hope that I have shown you a way forward for your friend, no finance and tax problems are insoluable.