Building Safety Act · Mandatory · Completion

Gateway 3 Completion Declaration

The completion declaration submitted to the Building Safety Regulator at Gateway 3.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. BSA 2022 / BSR Guidance remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	Building Safety Act 2022 + Building (Higher-Risk Building Procedures) (England) Regulations 2023
Status	Mandatory — HRB cannot be occupied until BSR issues Completion Certificate
BSR response time	8 weeks from complete application receipt
Occupation	Building cannot be occupied until Completion Certificate issued AND building registered with BSR
Criminal offence	Occupation before the completion certificate is a criminal offence

1. Gateway 3 — The Completion Gate for Higher-Risk Buildings

Gateway 3 is the BSA equivalent of practical completion for higher-risk buildings — but with significantly greater rigour. Where traditional practical completion is a contractual milestone agreed between the contractor and the employer, Gateway 3 is a statutory process where the Building Safety Regulator independently verifies that the building has been constructed as designed and approved at Gateway 2, and that all safety-critical information is in place before occupation is permitted.

The Gateway 3 completion declaration is the PC's and PD's formal statutory declaration that the building complies with the approved design and Building Regulations. It is accompanied by the completed golden thread — the accumulated evidence from construction that the building was built as specified. The quality of the golden thread throughout construction directly determines the completeness of the Gateway 3 package.

No HRB can be legally occupied before the BSR Completion Certificate is issued and the building is registered — not even for a single resident

The Building (Higher-Risk Building Procedures) (England) Regulations 2023 make it a criminal offence to permit occupation of an HRB without the BSR Completion Certificate and BSR registration. This applies to all residential occupancy — not just formal tenancies. Developers must ensure that the programme for any HRB includes the 8-week Gateway 3 assessment period and BSR registration before any resident moves in. Phased handover of blocks in a development may require separate Gateway 3 applications for each block.

2. Gateway 3 Completion Declaration — Content

The following components must be included in the Gateway 3 completion declaration submitted to the BSR.

Component	Description
PC declaration	Declaration by the Principal Contractor that: the building work is complete; the work has been carried out in accordance with the plans approved at GW2; all approved changes have been incorporated; the building complies with all applicable Building Regulations requirements. PC name, signature, date. CIOB/RICS registration number.
PD declaration	Declaration by the Principal Designer that: the design has been monitored throughout construction; to the best of their knowledge, the design information provided complies with all applicable Building Regulations requirements. PD name, signature, date. Professional registration.
Golden thread	Complete golden thread document register confirming all required information is present, current, and digitally accessible.
As-built information	Confirmation that as-built drawings, specifications, and change records are complete. See J18.
Fire and emergency file	Complete fire safety information package. See K7.
Test records	Evidence that all required tests have been completed: fire alarm; sprinklers; MEP commissioning; air tightness. See J category.
Key building information	Prescribed key building information per 2024 Regulations: height; storeys; number of dwellings; floor plans; external wall info.
Handover to PAP	Confirmation that the PAP has received the golden thread. PAP acknowledgement.

3. Common Mistakes

Not factoring the 8-week Gateway 3 assessment into the programme

The 8-week BSR assessment begins from receipt of a complete application. Incomplete applications are returned, resetting the clock. The programme must realistically account for: pre-GW3 preparation time; 8-week assessment; BSR registration; before occupation. Many developers have been surprised by this timeline impact.

Not maintaining the golden thread throughout construction

The Gateway 3 package is only as good as the golden thread that was built during construction. A golden thread assembled in the final weeks before Gateway 3 is incomplete, potentially inaccurate, and may not satisfy the BSR. The golden thread must be maintained from day one.

Assuming contractual practical completion = ability to occupy

Contractual practical completion is not the same as the ability to occupy. An HRB that reaches practical completion under the building contract cannot be occupied until the BSR Completion Certificate is issued and BSR registration is complete. Development agreements and lease obligations must reflect this — occupation obligations cannot be tied to practical completion dates for HRBs.

Not engaging the PAP before Gateway 3

The golden thread is handed to the PAP at Gateway 3. The PAP needs to be ready to receive and use the golden thread from day one of occupation. Early engagement of the PAP — well before Gateway 3 — ensures the format, access arrangements, and content of the golden thread are understood and suitable.

Not addressing BSR queries on the GW3 application promptly

The 8-week assessment period is a maximum, but the BSR may raise queries that require contractor or designer response. Slow responses to BSR queries will delay the completion certificate. The PC and PD must be prepared to respond rapidly during the assessment period.

4. Frequently Asked Questions

What happens if the BSR rejects the Gateway 3 application?▾

If the BSR is not satisfied that the building work complies with the approved plans or Building Regulations, it may refuse to issue the Completion Certificate. The applicant would need to: address the specific concerns raised; potentially carry out remedial works; and resubmit. There are appeal rights against BSR decisions. The building cannot be occupied during the appeal period.

Can a phased Gateway 3 application be made for large developments?▾

Where a development comprises multiple HRB blocks, a separate GW3 application is required for each HRB (each block). This enables phased occupation — later blocks can be submitted for GW3 when they are ready, while earlier blocks are already occupied. The programme for each block must include the 8-week assessment period before occupation.

What is the Building Assessment Certificate and how does it relate to GW3?▾

The Completion Certificate (issued at GW3) allows occupation and registration. The Building Assessment Certificate (BAC) is a separate, subsequent requirement for occupied HRBs — it is issued by the BSR following assessment of the building’s safety management arrangements and Safety Case Report. The PAP applies for a BAC when directed by the BSR. The BAC must be displayed in the building and renewed periodically. See K10.

What is ‘key building information’ required for Gateway 3?▾

The Higher-Risk Buildings (Key Building Information etc.) (England) Regulations 2023 define the key building information that must be submitted. This includes: building address; height in metres; number of storeys; number of residential units; building registration number; names and contacts of accountable persons; identity of the PAP; details of the building’s external wall system; details of any other fire safety or structural information specified.

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