Completion Day Is Only the Beginning: The 60-Day CGT Return for Second Homes in 2026/27

Completion is a milestone, but for Capital Gains Tax it is also a starting gun. When a UK residential property that is not your main home is sold at a gain, the seller generally has 60 calendar days from completion to report the disposal to HMRC and pay any CGT due. That return sits alongside, not instead of, the usual Self Assessment process. For sales completing in the 2026/27 tax year, the clock may already be running.

The 60-day window begins at completion

The date of exchange matters for some property and tax purposes, but the 60-day reporting deadline for UK residential property is measured from completion. A sale completing on 10 November 2026 therefore needs to be reported and paid by 9 January 2027. Weekends and bank holidays do not extend the window. It is sensible to diarise the deadline at exchange and confirm it again on completion.

The return is often called the UK Property Disposal return, or the 'CGT on UK property' service. It is separate from Self Assessment. Even where a seller already files a Self Assessment return, the 60-day property return is still required where a chargeable gain arises and tax is payable. The same disposal then needs to be included in the Self Assessment return for the relevant tax year.

Calculating the chargeable gain

Start with the disposal proceeds. Deduct allowable selling costs such as estate agency fees, legal fees, advertising and the cost of conveying the property to the buyer. Then deduct the acquisition cost: the original purchase price, Stamp Duty Land Tax, legal fees, survey and valuation fees, and other incidental purchase costs.

Capital improvements can also be deducted, but repairs and maintenance cannot. An extension, a new roof or a significant upgrade may count as enhancement expenditure if it is still reflected in the property at sale. Replacing a worn-out boiler or repainting the hallway is usually revenue repair, not a capital improvement. Records matter here: HMRC will expect invoices and a clear link between the work and the property.

Once the gain is calculated, deduct any allowable capital losses and the annual exempt amount. For 2026/27, the annual exempt amount is £3,000. Residential property gains are then charged at the CGT rates for residential property, currently 18% and 24%, depending on the seller's taxable income and the size of the gain. The rate is not automatic; it depends on how the gain stacks up against income and the available band.

Where the gain is covered by the annual exempt amount or reliefs, a 60-day return may not be required for a UK resident, but the disposal may still need to be reported in Self Assessment if a return is filed. Non-UK residents face different rules and must report disposals of UK property within 60 days even where no tax is due. If there is doubt, take advice before assuming no return is needed.

When Private Residence Relief can reduce the bill

Private Residence Relief is available for the periods when a property was the seller's only or main home. If the property has been a main home at some point, the final nine months of ownership are generally exempt. That final-period relief can be valuable, but it does not turn a pure second home into a main residence.

If the property was once the seller's main home and later let out, only part of the gain may qualify. Lettings relief is now limited to periods when the owner shared occupancy with a tenant. It is not a general relief for every buy-to-let. Periods of absence, working away or overseas living may also affect the calculation under specific rules.

A married couple or civil partners can generally have only one main residence between them for the same period. If a second home was never lived in as a main home, Private Residence Relief will not apply. Keep evidence such as council tax records, utility bills, electoral roll entries and correspondence showing which property was the main home.

The records HMRC expects

A practical file should include:

• the completion statement and sale contract;
• the original purchase documents and completion statement;
• the Stamp Duty Land Tax return or payment evidence;
• legal, survey and valuation fees from the purchase;
• estate agency, legal and advertising costs from the sale;
• invoices for capital improvements, clearly marked as such;
• records of any lettings and periods of occupation;
• evidence supporting Private Residence Relief if claimed;
• calculations of losses, the annual exempt amount and the taxable gain.

Keep these records for at least six years after the end of the tax year in which the disposal is reported. HMRC can ask questions later, and a well-ordered file is far easier to defend than a reconstruction from memory.

Filing and paying within 60 days

The return is filed through HMRC's online service using a Government Gateway account, or by an agent. The seller will need the property address, completion date, proceeds, allowable costs, gain, reliefs, losses and the annual exempt amount. Income details are also needed to work out the correct CGT rate.

Payment must reach HMRC by the same 60-day deadline. A bank transfer made on the final day may not clear in time. If cash flow is tight, contact HMRC before the deadline rather than after it. Late payment interest and penalties can build quickly, and ignoring the deadline rarely improves the position.

If the deadline is missed

HMRC can charge a £100 fixed late filing penalty. After three months, daily penalties of £10 can apply, up to £900. Further penalties of £300 or 5% of the tax due, whichever is greater, can arise at six and twelve months. Late payment penalties can apply at 30 days, six months and twelve months, alongside interest.

A reasonable excuse may be accepted, but it must be genuine and raised promptly. Illness, bereavement, postal failure or reliance on poor advice may be considered, depending on the facts. The key is to act as soon as the problem is identified rather than waiting for HMRC to make contact.

A practical checklist

• Confirm the completion date and diarise the 60-day deadline immediately.
• Gather purchase, sale and improvement records before calculating the gain.
• Consider whether any period qualifies for Private Residence Relief.
• Deduct allowable losses and the £3,000 annual exempt amount where available.
• File the UK property return and pay the tax within 60 days.
• Include the disposal in the 2026/27 Self Assessment return where required.
• Keep the full file for at least six years.

For second-home sellers, the central lesson is simple: completion is not the end of the paperwork. The 60-day CGT return is a separate deadline with its own penalties, and it rewards sellers who calculate early, keep records and pay on time.