What to cancel and how?
FYI you can only deregister a week prior you leave Germany. Some blogs say 2 weeks but no.
Some good tips here.
You can find the reregistration form online translated so I would recommend to print the English version to go to the reregistration office so then you can easily fill the German one.
You have to go to the local vehicle registration office (Kraftfahrzeugzulassungsstelle). Some info here.
My advice is to plan a lot of time to go there because it takes a lot of time, even if you have it all ready. If you are more an early bird than me go there before the opening and cue there first.
If you sell your car, I would recommend to go to this person if possible to the registration office so everything is done at once (contract + car deregistration). This can keep the same car plates and no need to take them off then.
Once you quit, your company will send a notification to the health insurance and it should be cancelled automatically. Nevertheless, it is better to also send a proof of employment contract end and of your reregistration to your local insurance office.
When you deregister your car (you have to do it anyway, in Germany or once back in your country when you change plates) it will automatically send a notification to your insurance.
Double check you are reimbursed at the pro-rata if ever you pay by year.
I would recommend to deregister while you are still in Germany because it is free and once you are in another country it is up to 200euros for the paperwork.
Habitation insurance: Same, your reregistration should directly send a notification to your insurance but double check with them.
If you rent a furnished flat it is usually 3 months prior to departure that you have to notify your landlord. Check your contract anyway, it should be written.
You need a proof from your landlord that you left the apartment.
You need to cancel gaz and electricity and internet contracts, do it asap because it can take time.
Make sure you get the caution back!
You also need the overview of taxes and bills of the flat for when you have to do your taxes.
ANY FIDELITY CARDS!!
For example your DB card! They ask you to notify them 6 weeks before the renewal date!
Gym member card? Public transport suscription? Just try to think about all your subscriptions :)
Do not close your account yet because you will receive money back (taxes, bonuses, habitation caution etc) and maybe you have to pay other things.
You king of have 4 options:
You do not have a lot and you just book extra luggages when you move out.
You send it all via DHL. Look at the pricing conditions because it costs the same to send a box of 19kg or 31kg!
You can also send parcels and it can be interesting.
You rent a car and drive you and your things. BUT be aware that if you leave in another country the “abandoned fees” are just huge! You also have to consider the gaz and the highway fees.
Contract a company, it is SUPER expensive but super practical.
You need your company to give you your U1 form.
I would recommend also to contact the national unemployment office to know about the specificities. For example there is.a high chance you have to ask for the U2 form.
You should also call the unemployment office of your nationally country to get the details of unemployment once you will be back.
For example as a French woman I have zero rights because I resigned. I cannot receive the unemployment payment and I lost my years working in Germany, just because I resigned… It sounds ridiculous especiallyy if keeping working was affecting your physical and mental health… Anyway, just check.
Super basic. do things asap. I know, it is boring, it is complicated etc etc but the more you wait the more difficult it is going to be! So get at it!
Think about printing things, we do not all have a printer home ;)
At last: positive thinking! It will be difficult, you know it, but you took this decision and you were strong enough for that so you will get through all those administrative details!