The signed Client Contract / Agreement must have a specific clause permitting the Manager to have any due publishing royalties etc., paid directly to them for onward allocation.
If songwriters are a member of a Performing Rights Organisation (PRO) such as PRS, BMI, ASCAP etc, they will receive 50% of all due royalties directly via their PRO paid directly to them and the Manager will receive 30%.
If not, then the Manager will receive 80% of all due royalties.
Any non-UK songwriters must be members of a recognised PRO.