The following information is regarding TuneCore's Publishing Administration service
It is sometimes possible to collect previously unclaimed royalties. However, TuneCore can make no guarantees on this. How successful this process is depends on the rules and regulations in place at the various collection societies and income sources around the world.
If you have previously had a publishing deal, this could also impact TuneCore’s ability to collect retroactively. That being said, it is not unheard of for unclaimed royalties to be collected for 2 - 3 years after the usage period.
Please ensure you have submitted all of your song information including co-writer names and shares along with ISRC codes and recording information such as artist name. The more information provided, the higher the chance of claiming any historical royalties. Unclaimed income would typically show up 2 - 3 quarters after the first distribution from joining TuneCore Publishing Administration.