| Northern Ireland Act 1998 | 1998 c. 47 | Act | amended | Tax Credits Act 1999 | 1999 c. 10 | s. 16 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | Appointed day(s) for spec. provns. | The Northern Ireland Act 1998 (Commencement No. 1) Order 1999 | 1999 No. 340 | art. 2 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | Appointed day(s) for spec. provns. (2.8.1999) (1.10.1999)(1.1.2000) | The Northern Ireland Act 1998 (Commencement No. 3) Order 1999 | 1999 No. 2204 | art. 1-4 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | Appointed day(s) for spec. provns. (28.10.1999) | The Northern Ireland Act 1998 (Commencement No. 4) Order 1999 | 1999 No. 2936 | art. 2 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | Appointed day(s) for spec. provns. (2.12.1999) | The Northern Ireland Act 1998 (Appointed Day) Order 1999 | 1999 No. 3208 | art. 2 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | Appointed day(s) for spec. provns. | The Northern Ireland Act 1998 (Commencement No. 5) Order 1999 | 1999 No. 3209 | art. 2 Sch. | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | | Northern Ireland Act 2000 | 2000 c. 1 | sch. para. 5(2) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | modified (cond.) | Northern Ireland Act 2006 | 2006 c. 17 | Sch. 2 para. 2(5) | See note |   This amendment not applied to legislation.gov.uk. Conditional amendment never in force |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | power to amend conferred | Northern Ireland (St Andrews Agreement) Act 2006 | 2006 c. 53 | s. 11(2)-(5) | Yes |   This affecting Act is amended (retrospectively) by Northern Ireland (St Andrews Agreement) Act 2007 (c. 4), s. 1(1) |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | modified | Northern Ireland (St Andrews Agreement) Act 2006 | 2006 c. 53 | s. 18(8) | Yes |   This affecting Act is amended (retrospectively) by Northern Ireland (St Andrews Agreement) Act 2007 (c. 4), s. 1(1) |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | excluded | Northern Ireland (Executive Formation and Exercise of Functions) Act 2018 | 2018 c. 28 | s. 3(7) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | modified | Northern Ireland (Executive Formation etc) Act 2022 | 2022 c. 48 | s. 1 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | excluded | Northern Ireland (Executive Formation etc) Act 2022 | 2022 c. 48 | s. 5(1) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | amendment to earlier affecting provision 2022 c. 48, s. 1 | Northern Ireland (Executive Formation and Organ and Tissue Donation) Act 2023 | 2023 c. 4 | s. 1(2)(b) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | modified by 2022 c. 48, s. 1A (as inserted) | Northern Ireland (Executive Formation and Organ and Tissue Donation) Act 2023 | 2023 c. 4 | s. 1(3) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Act | amendment to earlier affecting provision 2022 c. 48, s. 1 | Northern Ireland (Executive Formation) Act 2024 | 2024 c. 2 | s. 1 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Pt. 5A | inserted | The Protocol on Ireland/Northern Ireland (Democratic Consent Process) (EU Exit) Regulations 2020 | 2020 No. 1500 | reg. 2(2) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Pt. 5A heading | words substituted | The Windsor Framework (Democratic Scrutiny) Regulations 2024 | 2024 No. 118 | reg. 2(2) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Pt. 7A | inserted | Identity and Language (Northern Ireland) Act 2022 | 2022 c. 45 | s. 1(1) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Pt. 7B | inserted | Identity and Language (Northern Ireland) Act 2022 | 2022 c. 45 | s. 2(1) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | Pt. 7C | inserted | Identity and Language (Northern Ireland) Act 2022 | 2022 c. 45 | s. 3(1) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 24 heading | words omitted | European Union (Withdrawal) Act 2018 | 2018 c. 16 | Sch. 3 para. 55(a) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 24 heading | words inserted | European Union (Withdrawal) Act 2018 | 2018 c. 16 | Sch. 3 para. 55(b) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 24 heading | words omitted | The European Union (Withdrawal) Act 2018 (Repeal of EU Restrictions in Devolution Legislation, etc.) Regulations 2022 | 2022 No. 357 | reg. 3(4)(a) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(2) | words substituted | Northern Ireland (Miscellaneous Provisions) Act 2006 | 2006 c. 33 | s. 16(2) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(2) | words substituted | Northern Ireland (Miscellaneous Provisions) Act 2014 | 2014 c. 13 | s. 10(4) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(2A) | inserted | Northern Ireland (Miscellaneous Provisions) Act 2006 | 2006 c. 33 | s. 16(3) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(2A) | amendment to earlier affecting provision 2006 c. 33, s. 16(3) | Northern Ireland (St Andrews Agreement) Act 2006 | 2006 c. 53 | s. 18(5) | Yes |   This affecting Act is amended (retrospectively) by Northern Ireland (St Andrews Agreement) Act 2007 (c. 4), s. 1(1) |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(3) | words substituted | Northern Ireland (Miscellaneous Provisions) Act 2006 | 2006 c. 33 | s. 16(4) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(3A) (3B) | inserted | Northern Ireland (Miscellaneous Provisions) Act 2014 | 2014 c. 13 | s. 10(5) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(3C) (3D) | inserted | Northern Ireland (Miscellaneous Provisions) Act 2014 | 2014 c. 13 | s. 11(3) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(5A) | inserted | Northern Ireland (St Andrews Agreement) Act 2006 | 2006 c. 53 | s. 13 | Yes |   This affecting Act is amended (retrospectively) by Northern Ireland (St Andrews Agreement) Act 2007 (c. 4), s. 1(1) |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(6) | inserted | Northern Ireland (Miscellaneous Provisions) Act 2006 | 2006 c. 33 | s. 16(5) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 4(6) | amendment to earlier affecting provision 2006 c. 33, s. 16(5) | Northern Ireland (St Andrews Agreement) Act 2006 | 2006 c. 53 | s. 18(6) | Yes |   This affecting Act is amended (retrospectively) by Northern Ireland (St Andrews Agreement) Act 2007 (c. 4), s. 1(1) |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6 | applied by Regulation (EC) No 648/2004, Art. 15(7) (as inserted) | The Detergents (Safeguarding) (Amendment) (EU Exit) Regulations 2019 | 2019 No. 671 | reg. 3(4) | See note |   This amendment not applied to legislation.gov.uk. Affecting text in reg. 3(4) omitted (31.12.2020 immediately before IP completion day) by virtue of The Detergents (Amendment) (EU Exit) Regulations 2020 (S.I. 2020/1617), regs. 1(2), 3(2)(b)(ii) |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6 | applied by Regulation (EC) No. 1907/2006, Art. 4A(7) (as inserted) | The REACH etc. (Amendment etc.) (EU Exit) Regulations 2019 | 2019 No. 758 | Sch. 1 para. 5 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6 | applied by Regulation (EC) No. 1907/2006, Art. 129(9) (as inserted) | The REACH etc. (Amendment etc.) (EU Exit) Regulations 2019 | 2019 No. 758 | Sch. 1 para. 89(1) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6 | applied by Regulation (EC) No. 1907/2006, Annex 17 para. 2 (as inserted) | The REACH etc. (Amendment etc.) (EU Exit) Regulations 2019 | 2019 No. 758 | Sch. 3 para. 13 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6(2)(ca) | inserted | European Union (Withdrawal Agreement) Act 2020 | 2020 c. 1 | Sch. 3 para. 2 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6(2)(d) | words substituted | European Union (Withdrawal) Act 2018 | 2018 c. 16 | s. 12(5) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6(2)(d) | restricted | European Union (Withdrawal) Act 2018 | 2018 c. 16 | Sch. 8 para. 41(5)(9) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6(2)(d) | excluded | Immigration and Social Security Co-ordination (EU Withdrawal) Act 2020 | 2020 c. 20 | Sch. 2 para. 4(a)(b) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6(2)(d) | omitted | The European Union (Withdrawal) Act 2018 (Repeal of EU Restrictions in Devolution Legislation, etc.) Regulations 2022 | 2022 No. 357 | reg. 3(2) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A | inserted | European Union (Withdrawal) Act 2018 | 2018 c. 16 | s. 12(6) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A | power to repeal conferred | European Union (Withdrawal) Act 2018 | 2018 c. 16 | s. 12(9)-(11) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A | excluded | United Kingdom Internal Market Act 2020 | 2020 c. 27 | s. 10(6)(c) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A | excluded | United Kingdom Internal Market Act 2020 | 2020 c. 27 | s. 18(6)(c) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A | omitted | The European Union (Withdrawal) Act 2018 (Repeal of EU Restrictions in Devolution Legislation, etc.) Regulations 2022 | 2022 No. 357 | reg. 3(3) | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 6A(2) | words substituted | European Union (Withdrawal Agreement) Act 2020 | 2020 c. 1 | Sch. 5 para. 23 | Yes | |
| Northern Ireland Act 1998 | 1998 c. 47 | s. 7(1) | word repealed | Justice (Northern Ireland) Act 2002 | 2002 c. 26 | Sch. 13 | Yes | |