UK HMRC has released the Internal Manual on the Multinational Top-up Tax and Domestic Top-up Tax, dated 5 August 2025.

---

Summary

This manual covers Multinational Top-up Tax (MTT) and Domestic Top-up Tax (DTT). MTT is the UK's tax which implements the Income Inclusion Rule and Undertaxed Profits Rule, known widely the GloBE rules, outlined in the OECD's Pillar Two Model Rules. DTT is the …