German number plates (Kfz-Kennzeichen) show the place where the car carrying them is registered. Whenever a person changes their main place of residence in Germany, or buys a new car, they are required to buy new german plates. German plates can be bought which are valid all year round or between 2 to 11 months within any 12 months. This allows changing between summer and winter cars, such as a convertible and a sedan/saloon without having the time and money wasted for de- and re-registering. As of 2004, buying new German number plates normally costs around 30 Eurosfor de-registering the old german plates and registering the new ones. If a car is handed over to someone else permanently (e.g. sold), but stays within the same city/region, the number usually stays the same.

The present german number plate format, used since 1994, uses black print on a white background and first provides information about the country where the car is registered within the European Union. German number plates show a D (for Deutschland=Germany) on the blue strip on the left, which shows the European Union's flag, 12 golden stars in a circle on blue ground.
After that, there are between one and three letters which show the city or region where the car is registered, such as B for Berlin. These units usually coincide with the German districts, in few cases an urban district and the surrounding district share the same letter code. Usually if an urban district and a rural district share the code, the number of the following letters is different. For example, the urban district (Straubing) SR has one letter after the code (SR - A 123). The surrounding district Straubing-Bogen has two letters (SR - AB 123) after the code. It depends on the number of registered cars (or citizens) whether the City or the district has two letters, because there are more possibilities with two letters, so the part with more citizens usually has two letters. For example, the urban disctrict Regensburg has more citizens than the rural district Regensburg, so the city has two letters after the code R.

The number of letters in the city/region prefix code mostly reflects the size and location of the district: the largest German cities generally only have one letter codes (B=Berlin, M=Munich, F=Frankfurt), most other districts in Germany have two or three letter codes. Districts in eastern Germany usually have more letters, for two reasons:
As they only started using the modern system in 1990 after German reunification, many of the possible shorter combinations had already been used up in western Germany. Thus, big east German cities like Dresden have two letter codes (DD) instead of one (D) which was already in use for Düsseldorf.Fewer people live in eastern Germany, so the number of cars registered is smaller and hence the use of three letter codes.
This is only a rule of thumb, there are a number of exceptions e.g. Germany's second largest city Hamburg (HH, Hansestadt Hamburg, because of its membership in the Hanseatic League) or the west German district Ammerland (WST, Westerstede is the capital of the district).
The reason for this scheme is however not to display size or location, but simply to have enough combinations available within the maximum length of 8 characters per plate.
After the location name come the emission test and vehicle safety test stickers (see below), then one or two usually random letters followed by one to four usually random numbers. The total quantity of letters and numbers on the plate is never higher than eight. One letter with low numbers are normally reserved for motorcycle use since the plate space of these vehicles is smaller.

A problem with this scheme is that the space is a significant character and must be thought of when writing down a number. For example B MW 555 is not the same number as BM W 555. The confusion can be avoided by writing a hyphen after the city code, as in the old number plates, like B-MW 555. For this reason, the police will always radio the location name and spell out the next letters using the German telephone alphabet, which varies somewhat from the English one. Thus, B MW 555 would be radioed as "Berlin, Martha, Wilhelm, fünf-fünf-fünf".

If a car owner would like to buy personalised german plates, they tend to cost around €12 more than standard ones, depending on the region. Personalised german number plates must be applied for and must conform to the standards above. Car owners can choose certain numbers or letters instead of the random ones at the end. For example, people living in the town of Pirna might choose PIR-AT 77, "Pirat" being the German for "pirate"; another favourite is BAR-BQ 777 for Barnim, and WI-KI 777 would be a hit in Wiesbaden. Kiel is one of few places (others are Lauf, Regen, Daun, Brake, Baden or Ulm) where the number plate can be the city name: 'KI-EL' (KI-LL is also often seen). This works for the town of Heide in Dithmarschen, too, where HEI-DE is possible. Around Schwäbisch Hall (SHA) you can often see cars with the licence reading SHA-RK. Another possibility which many people choose is a combination of their initials followed by their year of birth, e.g. Peter Meyer born in April 1957 could try to get PIR-PM 57 or PIR-PM 457 when registering a car in Pirna. Almost every available combination with S-EX .... in Stuttgart and SE-X and SE-XY in Segeberg is in use as well. Also, some people choose a combination which reflects their car type, like BAR-T 601 for a Trabant 601 or BAR-TT 1 for an Audi TT. In Berlin, combinations like B-MW 1234 are common among owners of BMW cars. Other popular self-referential license plates include P-KW 000 in Potsdam and K-FZ 000 in Cologne: PKW is the German abbreviation for Personenkraftwagen ("car") and KFZ for Kraftfahrzeug ("motor vehicle"). The city offering the most possible combinations on license plates is Duisburg, which abbreviates to DU on license plates. Combinations such as DU-KE, DU-NE, DU-DE or even more insulting combinations such as DU-NG and DU-MB, as well as a number of German words, can be seen at every street corner in Duisburg. Danish citizens living in Darmstadt enjoy the combination DA-NE.

Prohibited combinations
Various combinations that could be considered politically unacceptable — mainly due to implications relating to Nazi Germany — are disallowed or otherwise avoided. The district Sächsische Schweiz uses the name of its main town, Pirna, in its code PIR, to avoid the use of SS, the name of the paramilitary organisation; similarly SA is also unused. This is why cars in service for the government and parliament in Sachsen-Anhalt are registered with LSA (Land Sachsen Anhalt). In 2004 in Nuremberg, a car owner was refused a number plate beginning N-PD because of the connection to the political party, the NPD.

Example of banned combination ("NS") which was issued accidentally.
Banned combinations include the Nazi abbreviations HJ (Hitlerjugend, Hitler Youth), NS (Nationalsozialismus, National Socialism), SA (Sturmabteilung), SS (Schutzstaffel) and KZ (Konzentrationslager, concentration camp). Some registration offices have overlooked this rule by mistake, however; there are a few cars registered carrying prohibited codes, such as B-SS 12. Some counties also allow these combinations if they are the initials of the owner (e.g., Nobert Schmidt might be able to get XX-NS 1234), but in this case, if the car is sold and re-registered in the same county by the new owner, the number can be changed (otherwise the number stays with the car until it registered in a different area).

History
The current system was introduced in West Germany in 1956, replacing the post-war system which was based on occupation zones.
As West German districts were extensively rearranged in the early 1970s, many prefix codes were expired and new ones were created at that time. However, number plates issued before these rearrangements remain valid, providing the vehicle is still in use and has not been reregistered since. So it is still possible, if rarely, to see registration codes of administrative units that haven't existed for over 30 years. Nowadays this is mostly limited to agricultural vehicles, old hangers etc.
When originally planned, the system included codes for districts in Eastern Germany which were to be reserved until reunification. That included the territory of the GDR as well as the territories annexed to Poland and the Soviet Union after World War II, which West Germany's government still claimed in that era. When reunification came in 1990, the reserved codes were indeed issued as originally planned to East German districts as they existed at that time. However, districts in East Germany were also rearranged in the mid-1990s, thus many of these codes have expired, but can likewhise still be seen on older vehicles.
One example of a reserved code being reused before reunification was the letter L which was originally planned for Leipzig, but was given to the newly formed Hessian district Lahn-Dill-Kreis in the 1980s. After reunification, the city of Leipzig successfully fought to get its L "back", Lahn-Dill-Kreis was issued with LDK instead after a changeover period when L was issued in both territories.

Typeface
Modern German plates use a typeface called FE-Schrift ("fälschungserschwerende Schrift", tamper-hindering script). It is designed so that the O cannot be painted to look like a Q, and vice versa; nor can the P be painted to resemble an R, amongst other changes. This typeface can also more easily be read by optical character recognition software for automatic number plate recognition than the old DIN 1451 script.
Special codes
Certain types of vehicle bear special codes:

Plate for vintage cars
§ vintage cars (known in German by the pseudo-English expression Oldtimer) have an H (historisch, historic) at the end of the plate, such as K-AA 100H

Seasonal german number plates, registration valid from 1st May to 31st October of each year
§ cars with seasonal number plates have two numbers at the end of the plate indicating the months between which they are registered to drive, with the licence being valid from the start of the upper month until the end of the lower month.

Official registered vehicle (here: fire brigade)

Official registered vehicle for disaster relief
§ Official cars such as police, fire fighting and municipality vehicles do not carry a letter after the sticker, such as M-1234.
These include:
vehicles of the district government: 1-199, 1000-1999, 10000-19999
vehicles of the local government (for example: fire brigade): 200-299, 2000-2999, 20000-29999, 300-399
police: 3000-3999, 7000-7999, 30000-39999, 70000-79999
disaster relief (mostly changed "THW", see below): 8000-8999, 80000-89999
consular corps: 900-999, 9000-9999.
Plate of tax-exempt vehicles
Vehicles which are exempt from vehicle taxes (for example ambulances, tractors, agricultural trailers, trailers for boats or trailers for gliders) have green print on a white background plate. Regular trailers can be tax exempt if the car owner agrees to hand over his trailer without payment to the armed forces (if Germany is in a state of emergency or defence).
Vehicles which have not been registered (because they are for transfer within Germany) have to carry short-term plates valid only for five days. The code starts with the numbers 04, e.g. DD-04000, and the plate has a yellow strip on the right showing when they are valid. The date is listed numerically, on three lines, reading day, month, year, with two digits each.

Special german plates (red colour, old DIN-style) for dealer's cars for test drives. (Registration office: Würzburg)
§ car dealers' plates are in red print on a white background, and the code begins with 06. Red plates may be attached to cars which are changing hands, such as the test run of unregistered cars, and the liability insurance is connected to the plate, not a specific car. Red plates starting with the number 07 are reserved for collectors of vintage cars. They must get an official certificate of approval (such as no criminal records). They are allowed to use one set of plates on any of their cars under the condition that they keep a strict record of use. No day-to-day use of the cars is allowed.
§ Export plates (also known as "Zollkennzeichen", customs german plates) are used for exporting vehicles abroad. The plates are the only ones which do not have the blue Euro strip on the left; the owner does not need to be a German resident to register the car. The date on the red strip on the right hand side does not show the expiry date of the german plate; instead it shows the expiry date of the vehicle insurance. After this date the vehicle must have left Germany.

Special plate for vehicles to be exported (Ausfuhrkennzeichen)

Special temporary plate for vehicles in Germany (Kurzzeit-Kennzeichen)

Former special german plate for vehicles to be exported (Zollkennzeichen) - no longer in use. It was replaced by the Ausfuhrkennzeichen in the 1980s
Diplomatic plates: plates of cars covered by diplomatic immunity have the digit 0 (Zero) on the left instead of the registration location code. This does not only include ambassadors of foreign countries: the German Federal President's license plate is 0-1, the Chancellor's 0-2, the Foreign Secretary's 0-3. The plate of the President of the Federal Parliament is an exception: it shows 1-1. This reflects the fact that the Parliament's President is not part of the executive branch but still ranks higher in (symbolic) importance than the Chancellor.
The military uses old style non-reflecting plates with a dash between the two circles. The German flag is shown, instead of the blue EU strip. Military plates use the letter Y, rather than a city indicator (no German city name starts with a Y). After the Y comes a six-digit number (or five digits for motorcycles), for example Y-123456
Military vehicles which are used by the Nato headquarters in Germany use the same design as the Y-plates except they carry the letter X followed by a four-digit number, for example X-1234
Some branches of the federal government and federal state governments use the abbreviations of their names instead of a city code. Example: the Technisches Hilfswerk (German Federal Agency for Technical Relief) uses its abbreviation THW, so the plates read THW-12345, for example. Before the Deutsche Bundesbahn (German National Railways) and the Deutsche Bundespost (Federal Post Office) were privatised, they used the abbreviations DB and BP (e.g. DB-12345, BP-12345).
The federal police uses the code BG (former name: Bundesgrenzschutz) (BG-#####) instead of the local code.
Light motorised vehicles such as mopeds and motorised wheelchairs are required to have a Versicherungskennzeichen ("insurance plate") on the back of their vehicle to prove that the vehicle is insured. This plate does not act as a proof of registration since this type of vehicle is exempt from official registration.
Insurance german plates

Versicherungskennzeichen, colour of the letters are changed yearly
The Versicherungkennzeichen used for mopeds and other small, low-power vehicles is much smaller than the plates for cars and is only valid for one year from 1st April to 31st March. There are four colours used: red for temporary use such as testing (very rare), black, blue, green for regular plates. The latter three colours are changed every year in order to make it easy to check whether the vehicle has the latest plate and hence is insured. Furthermore, the year is printed on the bottom line. Using the same colour plate three years later when the same colour is again valid does not work since the police can check the combination by radio and see whether the plate is valid for the current year or not. The system is three digits on the top and three letters beneath. The number and the letters are chosen randomly so personalising the plates is not possible (except by choosing from a small selection the insurer has in his office). Licences can be purchased with insurance companies who give them out together with a paid insurance.