No. Losing an ID card is not an offence and carries no fine, and a replacement document is issued free of charge. Liability arises from using someone else's document. The real cost of delay is not a penalty but the window in which someone can use your card.
Where the question comes from
Losing an identity document feels like a failure of a duty towards an office, so the first thought goes to a fine. The rules provide no penalty for the loss itself. The card simply ceases to be valid once you report it lost, and you apply for a new one.
What the actual problem is
Not a sanction but a window of time. Between losing the document and reserving your PESEL number and reporting the card to the Dokumenty Zastrzeżone system, your document is still circulating as valid. That window is when someone can try to sign an agreement in your name.
Criminal liability attaches to the person who uses someone else’s document, not to the person who lost it.
What a new ID card costs
An ID card is issued free of charge, including when the reason is the loss of the previous one. You apply at any municipal office or electronically, except where an in-person visit is required, for instance to take fingerprints.
While you wait, you can prove your identity with a passport, and in many domestic situations with an mDowód, provided you activated it earlier. After losing the plastic card activation is no longer possible, because it requires a valid ID card.
The order that matters
First reserve your PESEL number and report the document to the Dokumenty Zastrzeżone system. Then report the loss at the office, which invalidates the card. Apply for a new one last. Reversing that order carries no penalty, but it lengthens the window in which the document still looks valid.
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