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If you are a former Non-Dom sitting on foreign assets like a portfolio of US tech stocks or a holiday home in France selling them used to be a tax nightmare. Under the old rules, if you brought the proceeds to the UK, you would face tax on the entire growth in value since you bought the asset, potentially decades ago. As part of the 2025 reforms, the government has handed you a Reset Button. It is called CGT Rebasing.
This relief allows eligible individuals to rebase the value of their foreign assets to 5 April 2017. Effectively, any capital growth that happened before that date is wiped out for tax purposes. You only pay tax on the gain from April 2017 onwards.
This guide explains who qualifies, how to avoid the Dirty Capital trap, and why getting a retrospective valuation is your most urgent task.
What is CGT Rebasing?
Rebasing is a transitional rule designed to soften the blow for existing residents moving to the worldwide tax system. Normally, Capital Gains Tax is calculated as:
Standard Calculation
Sale Price – Original Purchase Price = Taxable Gain
Rebasing Rules
Sale Price – Market Value at 5 April 2017 = Taxable Gain
Confusion Buster Which Rebasing Date?
Do not confuse this rule with separate rules for Non-Residents selling UK property.
- 5 April 2015: Rebasing for Non-Residents selling UK Residential Property.
- April 2017: Rebasing for Non-Doms (The FIG Regime) selling Foreign Assets.
- 5 April 2019: Rebasing for Non-Residents selling UK Commercial Property.
If you are a UK resident selling foreign shares or overseas property, 2017 is your date.
Who Can Claim Rebasing?
Not everyone qualifies. To use this relief, you must meet all of the following criteria:
The Remittance History: You must have claimed the Remittance Basis of taxation in at least one tax year between 2017/18 and 2024/25.
Non-Dom Status: You must not have been UK domiciled (or deemed domiciled) before the 2025/26 tax year.
Asset History: You must have owned the foreign asset on 5 April 2017.
Disposal Date: You must sell (dispose of) the asset on or after 6 April 2025.
Personal Ownership: The asset must be held personally. Assets held inside offshore trusts or companies generally do not qualify for this specific relief (though other complex trust protections may apply).
Important: If you are a new arrival eligible for the 4-year FIG regime, you do not need rebasing. Your foreign gains are 100% tax-free anyway during your 4-year window.
Real World Example
Let’s look at the numbers to see the cash value of this relief. You bought a portfolio of Apple shares in 2010 for £100,000. You sell them in June 2025 for £500,000. The market value of the shares on 5 April 2017 was £350,000.
| Calculation Method | Cost Basis | Taxable Gain | Tax (at 20%*) |
|---|---|---|---|
| Standard Rule | £100,000 | £400,000 | £80,000 |
| New Rebasing Rule | £350,000 | £150,000 | £30,000 |
Result: Rebasing saves you £50,000 in tax.
Warning Dirty Capital Trap
This is the most dangerous aspect of the new rules that many advisors miss. While Rebasing fixes the tax on your profit, it does not automatically clean the money you used to buy the asset originally.
If you purchased that asset (e.g., the Apple shares above) years ago using un-taxed foreign income, that original capital (£100,000) is still considered mixed funds.
The Gain (Post-2017): Once you pay the CGT, this portion is clean and can be brought to the UK safely.
The Original Cost: This retains its original status. If it was dirty income when you bought the asset, it remains dirty now. Remitting this portion could trigger a 45% income tax charge.
You must segregate the funds upon sale. Bring the clean gain to the UK, but leave the dirty original capital offshore or use the Temporary Repatriation Facility (TRF) to clean that capital at 12%.
Critical Action Retrospective Valuations
You cannot simply guess what your asset was worth in 2017. If HMRC investigates your tax return, they will demand proof. To claim this relief, you need a professional Retrospective Valuation dated 5 April 2017.
- For Property: A surveyor’s report from that era, or a forensic valuation citing comparable sales from 2017.
- Unlisted Shares: A formal company valuation report.
- Listed Shares: Historic stock market data records.
Warning
If you cannot prove the 2017 value, HMRC may force you to use the original purchase price, drastically increasing your tax bill.
Frequently Asked Questions
Does this apply to UK assets?
No. Rebasing only applies to non-UK situated assets. If you sell a UK investment property, standard Capital Gains Tax (CGT) rules apply.
What is the tax rate?
Tax rates depend on the type of asset sold:
- Standard Assets (Shares/Funds): 10% (Basic Rate) or 20% (Higher Rate).
- Residential Property: 18% (Basic Rate) or 24% (Higher Rate).
- Business Assets: If you qualify for Business Asset Disposal Relief (BADR), the rate may be as low as 10% (subject to lifetime limits).
Allowance: You can also use your Annual Exempt Amount (currently £3,000) to reduce the gain.
Do I have to bring the money to the UK?
No. You do not need to remit the funds to trigger the tax. However, once you have paid the UK CGT on the sale, the remaining proceeds can be remitted freely (subject to the "Dirty Capital" warning above).
Conclusion
Get Your Valuations Now The Reset Button is a powerful tool, but it requires evidence. The further we get from 2017, the harder it becomes to get accurate valuations.
Thinking of selling an offshore asset?
Before you list it, Contact IBISS & CO to commission a 2017 valuation check and ensure you don’t accidentally remit dirty capital.
