You can apply for a WBS if you don't have enough money to rent a flat. Eligibility depends on how low your income is or if you receive social benefits (from the Jobcenter or other authorities). How much you are allowed to earn while still being eligible for a WBS depends on your federal state. The second important criteria is your residence permit: it needs to be valid for at least one year in Germany. The same apply if you have a student or work visa.
WBS: Affordable Flats in Germany
How can I rent a cheap apartment?
The WBS ("Wohnberechtigungsschein") is a certificate which entitles you to live in a state-subsidised flat. For these flats, the rent is considerably lower than the local average. This is possible because the landlords receive governmental financial support, e.g. when they need to carry out construction work or renovations. That way they can lower the rent and offer the flat to WBS-holders. If you hold a WBS, you gain access to this kind of cheap housing. Applying for a WBS is free of charge in some federal states, in others it costs between 4 and 40 euros.
The WBS only accords one room per person. That means if you are single, you will only receive a WBS for a one-room flat. A couple will receive a WBS for a two-room flat. In certain cases, it is possible for several people to combine their WBS's and rent out a flat with multiple rooms (depending on the number of WBS's). In Germany, the living room counts as one full room. Kitchen and bathroom are counted separately.
How to get a WBS
Am I eligible to apply?
What documents do I need?
How and where should I apply?
If you are unsure about which documents you need, you can still apply for a WBS. In case something is missing, your local Housing Office ("Wohnungsamt") will send you a letter and tell you what to add. If you are not entitled to a WBS, you can still apply for housing benefits ("Wohngeld") at your local Citizens' Office ("Bürgeramt" or "Rathaus").