Oops, it doesn't look like 'writing acknowledgement of invoice for writing day' is a national day..

Other days

Nae Nae Day

Ask Out Your Crush Day

Tell A Fairytale Day

Boba Day

Hiv Awareness Day

Get Funky Day

African Immigrant And Refugee Hiv And Hep Awareness Day

Bubble Bath Day

Ride The Wind Day

Hoodie Day