Selling a plot of land from your garden — whether to a developer for new homes, or to a neighbour who wants to extend their plot — is a disposal for Capital Gains Tax purposes. Many people assume that because it is part of their main home's grounds, there is no tax to pay. Sometimes there is not, but the conditions are stricter than most sellers expect.
It is a part-disposal
When you sell a portion of your land while retaining the rest (including your house), the transaction is a part-disposal rather than a full disposal. The CGT gain is calculated using a specific part-disposal formula:
The allowable cost attributed to the land sold is calculated as: (A / (A + B)) × total cost, where A is the proceeds from the land sold and B is the market value of what you retain.
This means you cannot simply allocate a proportion of the original purchase price by area. The formula uses market values at the time of the sale to determine the proportion.
Does Private Residence Relief apply?
PRR can apply to garden land, but only if the land meets the permitted area test. The permitted area is up to 0.5 hectares (about 1.24 acres) including the footprint of the house, or a larger area if HMRC accepts that a larger area was needed for the reasonable enjoyment of the property given its size and character.
If the garden plot you are selling is within the permitted area, PRR may fully cover the gain and there is no CGT to pay.
However, there is a key condition: the land must have been within the permitted area and used as garden or grounds throughout your period of ownership. If you previously let the land, used it for commercial purposes, or if it is development land that no longer forms part of the domestic garden at the time of disposal, PRR is not available.
The development land trap
Many people sell garden land specifically because it has development potential. This is where PRR often fails.
If the land is sold as a development plot — with planning permission granted or applied for, with a builder as the buyer, or on terms that indicate it is being sold for development — HMRC may take the position that the land is no longer part of the garden but is instead a separate asset.
The case law in this area is complex. HMRC's guidance refers to the requirement that the land be "enjoyed with" the dwelling. If the plot has been fenced off, is not cultivated, or is simply land held for future sale, it is harder to argue it is garden or grounds at the date of disposal.
If development land is sold without PRR applying, the full gain is taxable. Given the significant uplift in value that planning permission can create, this can result in a substantial CGT bill.
The 60-day return
If the garden land is a UK residential property disposal with a chargeable gain, the 60-day return applies. Garden land sold separately from a dwelling is within the scope of the 60-day rule where it is treated as a disposal of residential land.
If PRR fully covers the gain, there is no chargeable gain and no 60-day return is required (for UK residents). If PRR partially covers the gain, the residual gain may still be below the £3,000 annual exempt amount — in which case, again, no return is needed.
Planning the sale
Before agreeing a sale or granting an option to a developer, it is worth understanding the CGT position. If PRR is available in full, the sale is largely tax-free. If it is not, the gain could be significant.
Key questions to consider:
- Has the land been used as garden throughout your ownership?
- Is the plot within 0.5 hectares of the house?
- Does the plot retain its character as garden at the point of sale, or has it effectively become a development site?
- Have you applied for planning permission, which might indicate the land has left the domestic curtilage?
If you are selling garden land and there is a chargeable gain, the 60-day filing obligation starts on completion. Start your CGT return at LetsFile — a Chartered Accountant/Chartered Tax Advisor applies the part-disposal formula and assesses PRR eligibility before filing with HMRC.