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HMRC internal manual

Debt Management and Banking Manual

Pre-enforcement: coding out: class 2 NIC debts: National Direct Debit System (NDDS)

If you are setting up an arrangement using NDDS, and the taxpayer cannot locate their unique 18-digit reference from their payslip, use their National Insurance Number instead, minus the last digit. i.e. instead of “QQ123456A”, enter “QQ123456”.