The how, when and by whom relief can be claimed on losses.
Who is eligible?
Relief is available where a loan:
is made to a UK-resident borrower
is wholly for the purposes of a trade or to set up a trade, as long as they start trading
has not been assigned by the lender any right to recover that amount
is between the lender and the borrower who are not spouses or civil partners or companies in the same group when the loan was made or at any subsequent time CG65951
A trade includes ‘a profession or vocation’, but it does not include money lending. For example if a director lends the money to the company for the purchase of an investment property, this loan will be categorised as a non-qualifying loan for claim under s253 of TCGA 1992 and relief may not be available. The general rule of capital losses is that they can only be offset against capital gains.
Who can claim?
Capital loss relief can only be claimed by the taxpayer who made the loan. It was decided in HMRC v Execs of Mr Jeffrey Leadley  UKUT 0111 by the Upper Tribunal (UT). Where UT overturned the original decision of the First-Tier Tribunal (FTT) and established that executors of the deceased taxpayer were not entitled to make a claim under section 253 if the loan was already irrecoverable before the death of the lender.
Is your loan actually irrecoverable?
Relief is only due if the loan has become irrecoverable. HMRC looks closely at this type of relationship to ensure it meets the criteria for the relief. To satisfy the criteria, the claimant must be able to demonstrate:
that the borrower cannot repay the loan at the date the claim is made
that there was no reasonable prospect of the loan ever being repaid. If the borrower continues to trade this test is unlikely to be satisfied
that there was no indication at the time of lending the money that this would not be recovered
that the purpose of the arrangement involving the loan was not to secure tax relief.
When can you claim relief?
The relief is given by treating the amount outstanding as an allowable loss. Normally, you cannot claim that only part of the amount outstanding on a loan has become irrecoverable. You can make a claim if:
the borrower has been placed in bankruptcy, receivership or liquidation
the receiver or liquidator has announced an anticipated dividend in respect of unsecured debts and has indicated that no further dividends are likely
the amount of loan has been written off or released by waiver.
After the loan has become irrecoverable there is no time limit in which to make the claim. The loss will arise:
at the time you make the claim or, if you want
at an earlier time you specify when you make your claim that falls in either of the two previous tax years, provided all the necessary conditions for relief are satisfied at the date you make the claim and at the earlier time.
Do you have to pay back if recovered in future?
If you recover any amount for which you have claimed relief the amount you receive is treated as a chargeable gain. The chargeable gain arises in the tax year the payment is received and at the time of recovery.
Full HMRC manual guidance can be accessed here for details.