noun
Refers to the failure to pay a debt, tax, or other obligation. Often used in formal or legal contexts.
税金の不納が続くと、差し押さえの対象になることがあります。
Continued non-payment of taxes may result in seizure of assets.
不納のまま放置すると、延滞金が加算されます。
If left unpaid, late fees will be added.
Compound of 不 (fu, 'not') and 納 (nō, 'payment' or 'delivery'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of non-payment.