Why did National Pension sent me payment slips?

I have been working as a company employee continuously. Before I started working in my current company , I was working for another company and resigned on May 15. I started in my current company on May 27. Part of my Pre-Onboarding activities was to submit my pension number and since I lost it, I went to the Pension Office to do a 再発行。 When they saw that I was not working from 16-26 of May, they told me to apply for the pension for the number of days I was not working but told me that I do not need to pay anything. Just to declare..

Fast forward today, I received a payment slips from the National Pension amounting to 16,980 per month x 12.

I do not think I have to pay that, right? Can you please give me advice on what to do?

Thank you and regards.