Depending on where you come from, you may find the payment system for public transport here a little confusing at first. Most German municipalities use a modified honor system for travel on public transport. That means you buy your ticket or pass before you climb aboard, and you usually do not even have to show it when you enter. But don't forget to stamp your ticket either in the bus or train, or directly on the platform, before you start your journey. The exception is with buses, when you purchase your ticket directly from the driver. You have to board at the front of the bus and show your ticket or pass to the driver as you enter.
Tickets can be purchased at any customer center (KundenCenter) and ticket counter of participating public transport providers (in Düsseldorf, this is the Rheinbahn), or from private sales outlets and at ticket machines. You can either buy your tickets for individual trips or buy passes valid for periods of one day, one week, one month or even an entire year. The longer the period, the better the deal. VRR monthly passes (Ticket2000) are transferable, which allows you to lend them to friends or family members when you do not need them. In addition to being a better buy, the monthly tickets also have one important advantage over the weeklies: after 7 p.m. weekdays and all day on weekends, one adult and up to three children under 15 can travel free with a pass-holder.
Do not think, however, that the honor system is an open invitation to ride for free. It is, as we say, a modified honor system, and those who prove themselves not honorable can expect to pay a penalty. Teams of ticket inspectors, most often in plainclothes, travel around the system, prepared to catch miscreants traveling without a valid ticket or pass. Because inspectors wait until the train or bus has started rolling before demanding to see tickets, there is no way you can disembark and escape being caught.
If you are caught "traveling black" (schwarz-fahren), you will be asked to pay a fine of 40 euros on the spot. If you cannot pay right then and there, you will be handed a ticket with your fine listed on it indicating where you can go to pay that fine. If you do not pay within the period indicated, a notice will be sent to your address (that is why ticket inspectors insist on seeing your passport or some form of personal identity) with an increased fine. The longer you fail to pay the ticket, the more your fine will increase until, finally, you will be hauled into court. Better just to buy the ticket in the first place. If you feel you have a valid excuse for not paying your fine (just about the only one accepted is that the ticket machine at your station was not working), you can bring it up with the official at the payment office.
Do not try arguing with the inspectors; they are trained to disregard all pleas and sob stories and to leave the matter of appeals to the people at the payment office. The payment office has a chart listing all the ticket machines that were out of operation - and on what days - so make a note of the machine number or station. If the date and time on your fine do not match their records, you pay the fine; if it does, they waive the fine and apologize for the inconvenience you have suffered. Sorry, no money back for your trip to the office.