Local authorities can in certain circumstances apply to magistrates court for a warrant to commit the debtor to prison. This is a coercive measure designed to extract payment from someone with the means to pay. It is not a punishment for failure to pay the debt.
If the amount is paid before the warrant is issued or offered to the local authority it must accept the payment and no further action should be taken. If the amount owed is paid after the local authority has applied for the warrant but before it is issued or a term of imprisonment has been fixed and the issue of a warrant is postponed, a local authority may recover reasonable costs in connection with the committal proceedings.
A warrant to commit to prison is only issued if the court is satisfied that the failure to pay is:
Willful refusal by the debtor OR
Culpable neglect by the debtor AND
The debtor has means to pay the debt
The maximum period of imprisonment is three months, but the maximum period should be reserved for the most extreme cases eg deliberate refusal to pay.
Once a warrant for commitment to prison is issued the liability for Council Tax, including any joint liability must be written off. No further recovery action can be taken in relation to the relevant amount.