SDLT in Edgware: the family transfer trap that isn't market-value — it's mortgage assumption

Edgware is the borough's densest area for intergenerational family property transfers. A parent transferring a BTL to an adult child — whether as a gift, a 'sale' at an undervalue, or a succession planning move — is a routine HA8 event. Two tax misconceptions consistently attach to these transactions, both of which cost families five figures when mishandled. The first is the assumption that SDLT automatically applies at full market value on connected-party transfers between individuals. It does not. The second is the assumption that no SDLT means no tax event at all — which misses a separate CGT consequence on the parent, at market value, that has to be reported and paid regardless of what happened with SDLT.

The SDLT treatment is subtle. FA 2003 Schedule 4 paragraph 1 charges SDLT on 'chargeable consideration' — the actual money or money's-worth changing hands, not the property's value. Section 53 (the market-value substitution rule) applies only where the purchaser is a company, not an individual. A parent transferring a £450,000 HA8 BTL to an adult child for £100,000 cash with no other consideration would, on those facts alone, trigger SDLT on £100,000 — roughly £2,000 standard plus £5,000 surcharge (if the child owns other property), total £7,000. Not on £450,000. This is genuine, and it is a significant planning opportunity. But there is a catch that routinely blows the calculation up, and it is specifically why Edgware families get caught: mortgage assumption counts as chargeable consideration. If the £450,000 property has a £260,000 outstanding BTL mortgage which the child assumes on transfer, SDLT is charged on £100,000 + £260,000 = £360,000. That shifts the SDLT from £7,000 to approximately £28,000. The family discovers the difference after completion.

The CGT side is non-negotiable and is where generalist accountants most often fail Edgware families. TCGA 1992 s17 and s18 treat disposals between connected persons as happening at market value for capital gains purposes, regardless of actual consideration paid. The parent in the example above — who received £100,000 cash for a property worth £450,000 — is treated as if they had sold it for £450,000 for CGT purposes. On gains accrued since the parent's original purchase (often 15–25 years earlier for HA8 long-hold BTLs), the CGT bill can reach £60,000–£110,000. This liability falls on the parent, is payable within 60 days of completion via the HMRC online service, and exists entirely separately from any SDLT the child pays. Every Edgware family transfer is two tax events, not one, and both must be planned from the start.

The planning routes that work are mostly about structure chosen before execution. Where the intention is genuinely to help a child acquire property, a properly documented secured loan from parent to child (rather than a gifted equity transfer) leaves the parent as the owner for both SDLT and CGT purposes while giving the child effective access to the asset. Where a transfer is unavoidable, matching it to a year of otherwise-low parental income uses the basic-rate CGT band at 18% rather than 24%. Where the property is a let investment rather than a former family home, spreading the transfer across tax years — 50% now, 50% later — uses two annual exempt amounts and two basic-rate bands. These are not exotic tax-avoidance schemes; they are the default positions for competent Edgware family-transfer work, and they are almost always absent from the generalist accountant's advice.