Non-priority debts go in the DMP
Consumer credit debts are the natural fit for a DMP: credit cards, store cards, personal loans, catalogue accounts, buy-now-pay-later balances that have gone to collections, and overdrafts (though including an overdraft usually means the account will be closed).
Old mobile phone bills, utility arrears that have been sold to debt collectors, and old rental debts from previous properties can also be included.
Priority debts sit outside
Priority debts are those where the consequences of non-payment are worst: mortgage or rent (losing your home), council tax (bailiffs, potentially imprisonment in England), utility bills for current usage (disconnection), court fines (bailiffs, potentially prison), child maintenance (enforcement action), and TV licence (fines, potentially prosecution).
These are paid in full separately, before the DMP contribution. Your monthly disposable income after priorities is what funds the DMP.
HMRC and business debts
HMRC generally does not participate in DMPs. HMRC prefers direct Time to Pay arrangements — an instalment plan agreed with HMRC directly for Self Assessment or PAYE debts.
Business debts where you are a sole trader are treated like personal debts. Business debts for a limited company are the company's liability, not yours personally — unless you have given a personal guarantee.
Joint debts
Debts held jointly with a partner (joint credit cards, joint loans) can be included in a DMP but the other party remains fully liable. If you pay a reduced amount, the creditor may still pursue the other party for the shortfall.
This can complicate joint DMPs — sometimes couples set up plans together to cover both liabilities.