As the nearest relative of someone who has died, you must ensure that the death certificate is sent to both the district court and the local police (sheriff) in the municipality in which the deceased person lived. The funeral directors will normally help you to do this.
The district court will notify the National Registry of the death.
Division of inheritance
The reason why the death certificate must be sent to the district court is that the district court is responsible for dividing the estate of the deceased person. The division of a deceased person's estate means the distribution of the inheritance, i.e. what the deceased person left behind.
In Oslo, Oslo County Court is responsible for dividing up a deceased person's estate. Elsewhere in the country, the local district courts are responsible for this process.
Skatteetaten.no is not a searchable register of deceased people. On the website of Oslo County Court (Oslo byfogdembete), you will find an overview of registered deaths in Oslo.