The following set of rules will apply if you're a returning traveler from one of the countries mentioned in the RKI-Risikoland listing.
You'll have to register online (regardless of your means of transport when traveling) at www.einreiseanmeldung.de. You'll have to carry a written transcript of your registration details when traveling.
Please check the RKI-listing: If you're returning from high-risk countries in which mutated virus occurs frequently or where COVID-infections are abundant these rules will apply:
a) immediately before departure from abroad or straight after immigration into Germany, you'll have to get tested for SARS-CoV-2.
b) you have to inform your local Gesundheitsamt (health authority) about your travel itinerary
c) you have to start quarantining yourself immediately after arrival
d) you'll have to have another SARS-CoV-2 test done on day 5 or your quarantine. If that result is negative you can stop isolating yourself
For "standard" risk areas the following rules apply:
a) you'll be tested for SARS-CoV-2 within 48 hours before or straight after immigration into Germany
b) if the result is negative, quarantine will not be necessary
Costs for tests associated with travel activity will not be reimbursed by the German authorities. We offer to do all the required tests in our Praxis.
For more information take a look at the official NRW Coronavirus website