Background: With ageing of the population both prevalence of chronic kidney disease (CKD) and incidence of kidney replacement therapy (KRT) are rising. Existing research suggests that Read-coding for CKD in those affected is associated with better implementation of recommended care and fewer hospitalisations for heart failure. Aim: To investigate whether coding for CKD is associated with regional KRT incidence in England. Design & setting This is an ecological study using the clinical commissioning groups (CCG) in England as geographical units. Method: KRT incidence rates were calculated using UK Renal Registry (UKRR) data from 01/2019 to 12/2021. Data on the percentage of uncoded CKD patients (PUCP) who had laboratory evidence of CKD but lacked a diagnostic code were obtained from the CVDPREVENT Audit, a national audit that extracts routinely held general practitioner data. Data on confounders and acute kidney injury (AKI) mortality as a marker for population frailty were obtained from CVDPREVENT and the UKRR, respectively. Poisson models assessed the association between PUCP and KRT incidence. Results: After adjusting, the PUCP was non-linearly associated with KRT incidence, with the CCGs in the lowest PUCP quintile having a lower KRT incidence than the others. There was evidence that this association was more pronounced in CCGs with high AKI mortality compared to CCGs with low AKI mortality. Conclusion: At the geographical level in England, the data suggests that the prevalence of not having formally diagnosed CKD is non-linearly associated with a higher KRT incidence rate, especially in areas with a high AKI mortality.