There are three tax planning windows that matter for founders in the UK. Two of them are time-limited in ways that most founders do not understand until the window has closed. One of them is already closing for every founder who has not yet acted.
Window 1: The SSE qualifying period
Substantial Shareholding Exemption requires the holding company to have held at least 10% of the ordinary share capital of the trading company for twelve continuous months before the disposal. The clock starts when the holding company is installed and the shares are transferred into it.
For a founder who has not yet installed a holding company, the SSE qualifying period has not started. Every day without the structure in place is a day the clock is not running. A founder who receives an approach from a buyer and then installs a holding company has missed the window entirely — HMRC will not grant clearance for a share exchange that is part of a specific exit transaction.
The window is open now. It closes the moment a specific buyer approaches.
Window 2: The IHT seven-year clock
Potentially exempt transfers — gifts of assets to individuals — fall outside the estate after seven years. The clock starts when the gift is made. A founder who gifts shares in a FIC or a holding company to their children today starts a seven-year clock. If they survive seven years, the gift is outside the estate entirely.
A founder who waits until they are 70 to start gifting is running a seven-year clock from age 70. A founder who starts at 55 has the same seven-year clock, but with fifteen more years of compounding growth sitting outside the estate rather than inside it.
The window is open now. It closes with every year of delay.
Window 3: The constitutional architecture
The SAFO structure ring-fences future growth from the estate from the moment it is installed. Growth above the existing asset value accumulates inside the structure rather than inside the estate. The window for this is always open — but the cost of delay is the growth that accumulates inside the estate while the structure is not yet in place.
A business growing at 10% annually with £5 million of assets today will have £8.1 million of assets in five years. The £3.1 million of growth that accumulates without the structure in place is exposed to 40% IHT. That is £1.24 million of IHT on growth alone — growth that would have been outside the estate if the structure had been installed five years earlier.
The audit maps your position against all three windows. The number that changes when you act is the number that is currently accumulating while you wait.