No required number
A producer does not get a set percentage just because the role is called producer. If the producer is part of a joint work, the authors are coowners of the copyright in that work, and the statute does not set a percentage split. Use the number the team agreed on and record it clearly.
If you want a simple starting point, see the split sheet template and the related royalty split guide.
Composition versus master
A producer may have credits on the underlying musical work, the sound recording, or neither. Copyright law treats a sound recording as a separate category from the underlying musical work, so it helps to write down exactly what the producer contributed and which asset the split refers to.
For practical examples, the use cases page and the credit notes feature page show how to keep those notes organized.
Work made for hire caution
Employment is a different rule. For a work made for hire, the employer is considered the author unless the parties signed a written agreement that says otherwise, so do not assume the same split rules apply in every session.
If your project has a work made for hire agreement, write the terms down separately and keep them with the session records.
Write a sheet
Print the template, fill in the agreed credits, and save the PDF with the session. A producer split sheet pdf is most useful when it is easy to find later and matches the final credits everyone accepted.
After the session, keep the signed or saved PDF with your files so you can check it against the track metadata and any later royalty questions.
Not legal advice. Splitline does not grant a license, clear a sample, or pay royalties.