Stage 6: Completion & Moving In
You are nearly there. But completion brings its own checklist - including a VAT reclaim deadline that cannot be missed and a mortgage that needs switching within weeks.
You are nearly there. But completion brings its own checklist - including a VAT reclaim deadline that cannot be missed and a mortgage that needs switching within weeks.
The final Building Control inspection formally signs off your home as compliant with Building Regulations. The inspector will check that all outstanding items from previous inspections have been resolved, that the electrical installation certificate has been provided, that the heating system has been commissioned, and that the building matches the approved plans.
The Completion Certificate is issued after sign-off. This is one of the most important documents in your self-build - keep it safely. You will need it for:
Under HMRC's DIY Housebuilders Scheme (Form VAT431NB), self-builders can reclaim VAT paid on eligible building materials. The reclaim must be submitted within three months of the date of the Completion Certificate. There is no extension and no appeal - miss it and the money is gone.
The reclaim covers VAT on materials that become part of the permanent fabric of the building. It does not cover professional fees, plant hire, or some specialist items. For a standard self-build the reclaim is typically £15,000-40,000.
Read our full VAT Reclaim guide for a complete list of eligible items, how to prepare the claim, and common mistakes to avoid. Start preparing the paperwork now - do not wait until the last week.
You have three months from the date on your Completion Certificate to submit Form VAT431NB to HMRC. Missing this deadline means permanently losing the reclaim - typically £15,000-40,000. Submit as soon as all receipts are collated, well before the deadline.
Your self-build mortgage was structured for the build phase - stage releases at a higher interest rate. On completion, you need to switch to a standard residential mortgage. Most self-build lenders have a completion product, but you are not obliged to stay with them - shopping around at this stage can save significant money over the long term.
Your lender will require the Completion Certificate and a final valuation of the completed property before releasing the final stage payment and switching to the standard rate. Allow two to four weeks for this process.
Your site all-risks insurance policy covers the building during construction. It does not cover a completed, occupied dwelling. You must arrange standard buildings and contents insurance before you move in - the two types of policy cannot overlap but must not leave a gap either.
Arrange the standard buildings insurance to start from the date of the Completion Certificate. Shop around - a newly built property in your own name may attract favourable premiums.
You must register for council tax with your local authority as soon as the property becomes habitable - which is typically when it receives its Completion Certificate. Most councils will back-date the liability to this date if you register late, so there is no benefit in delaying.
A newly built property will be assessed for its council tax band by the Valuation Office Agency. The assessment is based on what the property would have sold for on 1 April 1991 (the reference date for the current banding system), adjusted to current values. You can challenge the banding within six months of first assessment.
Your temporary construction supplies (usually on a site meter) need to be switched to permanent accounts. Contact each utility company to switch the account into your name, provide meter readings, and close the construction account. This applies to electricity, gas (if connected), water, and if relevant, broadband.
Your structural warranty provider should issue the warranty certificate within a few weeks of final Building Control sign-off, provided all stage inspections were completed. Check the certificate is issued in the correct name (yours, not the contractor's) and covers the full 10-year term.
Keep the warranty certificate with your Completion Certificate and your building's operation and maintenance manual. You will need all three when you sell the property.
If you used the Help to Build equity loan scheme, you must submit a completion claim to Homes England within six months of the Completion Certificate. Failure to do so puts you in breach of the equity loan terms. The completion claim confirms that the build is complete and triggers the formal equity loan documentation.
Your contractor has a defects liability period under the build contract - typically six to twelve months - during which they are obliged to return and fix any defects that emerge. Report defects in writing as they appear. Do not pay the final retention until all defects from the snagging list are resolved.
Keep a written record of every item you report and every response you receive. If the contractor fails to respond within a reasonable time, you may need to appoint a replacement contractor and recover the cost from the retention or bond.
Confirm with your solicitor that the title register has been updated correctly to reflect any mortgage charge and your ownership. This should have happened automatically at purchase, but check - particularly if there were any changes to the mortgage during the build.
Ready to tick off these completion tasks? Go to Stage 6 in your project checklist - your progress is saved automatically.