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Spotlight PEPPOL BIS Billing 3.0 The EU e-invoicing mandate is here — France Sept 2026, Belgium Jan 2026, Germany 2025.

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MT501 — Confirmation of Registration or Modification

The register inscription confirmation. The transfer agent replies to the custodian that the operation requested by MT500 is effective, refused or partially applied — with the legal inscription date that serves as the pivot for the rights attached to the security.

Purpose

MT501 closes the loop opened by MT500. Four statuses are possible in the :25D::REGS// qualifier:

  • REGI — Registered. Registration confirmed, the registered holder is officially the new owner.
  • REJT — Rejected. Registration refused (KYC failed, missing document, security not eligible). Detailed reason in :24B:.
  • PEND — Pending. Awaiting further documents or final verification.
  • PACK — Partial Acknowledgment. Partial registration (quantity accepted < quantity requested).

On US markets, the :98A::REGI// date is the record date that determines the rights attached to the security (dividends, AGM votes, preferential subscription rights). A discrepancy between the requested date in MT500 and the confirmed date in MT501 is legally significant and must be traced.

Sequence structure

  • GENL — General Information: MT501 reference (SEME) and the original MT500 reference (RELA — Related Reference).
  • CONFDET — Confirmation Details: :25D::REGS// status, security, confirmed quantity, effective date.
  • REGDTL — Registration Details: registered holder identity (carried over from MT500) and narrative block for registrar information (DTC participant number, Computershare identifier…).

Block 4 tags

TagNameFormatUsage
:20C:Reference:4!c//16xSEME (MT501 reference), RELA (linked MT500 reference).
:23G:Function4!c[/4!c]NEWM (new confirmation), CANC (cancel a prior confirmation).
:25D:Status Code:4!c/[8c]/4!cREGS//REGI (Registered), REGS//REJT (Rejected), REGS//PEND, REGS//PACK.
:98A:Date:4!c//8!nPREP (confirmation prep), REGI (effective registration date).
:35B:Instrument4*35xISIN carried over from MT500.
:36B:Quantity:4!c//4!c/15dREGI (effectively registered quantity — may be < requested).
:97A:Account:4!c//35xSAFE (source safekeeping account).
:95P: / :95Q:Party IdentificationvariesREGI (registrar BIC), BENM (registered holder).
:24B:Reason Code:4!c/[8c]/4!cIf REJT: REJT/DSEC (security not eligible), REJT/INDC (incomplete data), REJT/KYCM (KYC missing)…
:70E:Narrative10*35xREGI/… — registrar information (participant number, ledger ID).

Real-world example

Citi → BNP Paribas confirmation that the 5,000 IBM shares are registered under the John Smith Family Trust name, effective date 18 May 2026 (2 business days after the 16 May MT500 instruction):

text mt501-confirmed.txt 
{1:F01CITIUS33XXXX0000000000}{2:I501BNPAFRPPXXXXN}{3:{108:CFR20260518001}}{4:
:16R:GENL
:20C::SEME//CFR20260518001
:20C::RELA//REG20260516001
:23G:NEWM
:98A::PREP//20260518
:16S:GENL
:16R:CONFDET
:25D::REGS//REGI
:98A::REGI//20260518
:35B:ISIN US4592001014
IBM CORP
:36B::REGI//UNIT/5000,
:97A::SAFE//IBMHOLDREG-001
:95P::REGI//CITIUS33XXX
:16R:REGDTL
:95Q::BENM
JOHN SMITH FAMILY TRUST
123 MAIN ST
NEW YORK NY 10001
:70E::REGI//DTC ACCOUNT 0902 PARTICIPANT REGISTRATION COMPLETED
:16S:REGDTL
:16S:CONFDET}
  • :20C::SEME//CFR20260518001 — MT501 internal reference.
  • :20C::RELA//REG20260516001 — original MT500 reference.
  • :25D::REGS//REGI — Registered status (registration confirmed).
  • :98A::REGI//20260518 — legal registration date, serves as record date.
  • :70E::REGI// — narrative DTC participant 0902 — useful for custodian reconciliation.

Common pitfalls

  • Missing RELA — without :20C::RELA//, the custodian cannot reconcile the confirmation with the original instruction. An MT501 without RELA is usually rejected by bank ETLs.
  • Undocumented partial quantity — if :36B::REGI// is below the amount requested in MT500, the status must be PACK and a :70E: must explain why. Otherwise the custodian considers the remainder pending.
  • Retroactive REGI date — the effective date cannot be earlier than the MT500 date. A retroactive :98A::REGI// is rejected by custodian compliance checks.
  • REJT vs PACK confusion — a partial rejection (PACK) is not a total rejection (REJT). The custodian must treat the two quantities separately: the registered part moves to holdings, the remainder stays in street name.
  • Silent BENM modification — if the transfer agent edits the beneficiary (typo correction), :25D: must shift to AMEN with an explanatory narrative. A silent modification is a KYC breach.

ISO 20022 equivalent

  • sese.024 — Securities Settlement Transaction Status Advice with SctiesTxTp=REGT, status MTCH (matched) or SETT (settled).
  • reda.002 — Reference Data Reporting Response, register maintenance side.
  • Transfer agents largely continue using MT500/MT501 with no mandatory ISO 20022 migration in 2026.
  • MT500 — Instruction to Register, the trigger instruction for MT501.
  • MT535 — Statement of Holdings, the statement that will show the registered position.
  • MT564 — Corporate Action Notification, triggered for events on registered securities.
  • ISO 20022: sese.023, sese.024.