Abstract New carbon isotope results obtained from cores from the Fehmarn Belt (German Basin) and hitherto non-published, detailed results obtained from brachiopods collected in the 1970s from the Hemmoor section, NW Germany, present the opportunity to revise the holostratigraphy of the Danish Basin and erect a complete chronostratigraphical scheme for the upper Campanian-Maastrichtian of the Boreal Realm based on records from the Danish and North German Basins. The correlation of all studied sections is ensured by previously erected high-resolution bulk carbonate carbon isotope records. A number of issues arising from the standard UC calcareous nannofossil biozonation scheme for the Boreal Realm are discussed and lead us to propose a new subzonation for the Danish Basin. Carbon isotope records allow correlation to Gubbio, Italy, the Tethyan bio-magnetostratigraphic reference, and to the astronomically calibrated ODP site 762C, Indian Ocean. Revised correlations ensure the application of magnetostratigraphy, a numeric time scale and stacking of 405 kyr cycles to the new scheme, thus erecting a detailed chronostratigraphy for the upper Campanian - Maaatrichtian of the Boreal Realm. Supplementary material at https://doi.org/10.6084/m9.figshare.c.7198031