SWIFT ISO 15022 - Code TREATBENF Meaning Claim of Tax Treaty Benefits Usages Message type Field number Tag MT574.W8BENO (IRS 1441 NRA-Form W8-BEN) 20 16R (Start of Block) MT574.W8BENO (IRS 1441 NRA-Form W8-BEN) 24 16S (End of Block)