Diagnosis
Employee National Insurance arrears which originated in the previous taxyear remain at the end of the current tax year. These arrears can nolonger be claimed back from the employee.
Under current NI rules, employees can carry forward NI arrears to thenext tax year only once. If an employee's arrears are not fully deductedby the end of the subsequent tax year, they cannot be carried forwardany further and become the liability of the employer.

See also
National Insurance Arrears