The short answer
With a split ticket, you buy separate tickets for two parts of a journey instead of one through ticket. You may remain on the same train. Because each part is priced separately, the combined fare can be lower.
The idea gained attention through one example that was 84% cheaper. Cases that extreme are rare. Whether splitting helps on your connection depends on the saver-fare inventory available that day.
What the measurements found
The latest Bahnsparer test priced six long-distance connections and 32 possible split points. The through ticket was cheaper in every case.
Lower-priced splits do exist. One specialist test found differences of €10 to €18 on individual routes; the well-known extreme case was 84%. The saver fares still available on each segment that day make the difference.
That matches independent testing. Stiftung Warentest concluded that split tickets only rarely save money and often make the journey more expensive.
Bahnsparer therefore makes no promise of a saving. The app either shows a lower-priced split with both segment fares or, when the through ticket wins, how many stops it checked.
When it can work
Whether a split costs less depends on the saver fares still available for each segment. That can change every day, so there is no reliable rule of thumb.
Long journeys offer more possible split points. If one segment uses regional transport, also check whether your Deutschlandticket already covers it.
The protection you give up
Each part of a split is a separate ticket, and passenger rights apply to each ticket separately. A through ticket covers the whole journey; with two tickets, the first operator's responsibility ends at the split point.
If you stay on the same train, there is no connection to miss. If the split point is a transfer and the first train is late, the second ticket does not protect the onward journey because it is a separate contract. Every Bahnsparer suggestion identifies which case applies.
Check your journey without doing the maths
Select your connection, open “Details” for one direction in the summary, then choose “Split-Ticket prüfen”. The app prices possible split points and shows lower-priced options with the best first. If the through ticket is cheaper, it shows how many stops were checked instead. You book with the provider, whose checkout price is binding.