If you have spent weeks talking to an investor introduced as a family office, the question worth asking before cheque size is who will legally sign for the shares. SEIS and EIS were written for individual taxpayers, and family office investors arrive in a range of structures that do not always fit that description.

A fundraise that assumes tax relief for every name on the cap table can learn otherwise after the money has moved and HMRC has been asked to confirm the relief.

We set out the basics below so you can ask the right questions early and hand the details to your accountant.

Who family office investors are and how they hold shares

Family office investors are a loose group.

A single-family office manages the wealth of one family, often created by a company sale or a long-running family business, and it invests through whichever structure the family’s advisers have set up.

A multi-family office pools the affairs of several families.

Some of these investors are founders turned backers. Dig Ventures began as a family office for Ross Mason, the MuleSoft founder, after he exited the company in 2018 and moved back to the UK, and it has since been raising a first venture fund from outside investors. Founder-led offices of this kind can behave much like angels, though usually with deeper pockets.

“Introductions to family offices are very network-driven”— Melissa Lester, Dig Ventures

The office and the person behind it are not the same thing, and that distinction matters below. Guillaume Poussaz, the Checkout.com founder, moved to Monaco in April 2025, but the single-family office he set up, Zinal Growth Partners, was reported in August 2025 to be staying in London.

The UK is a busy market for this capital. It ranked second globally, behind the US, for family office startup deals between July 2023 and June 2024, so family office investors are fairly likely to appear in a UK founder’s pipeline. They also tend to invest alongside others: 83% of family offices’ startup investments worldwide in the first half of 2024 were club deals, so your fundraise may combine several investor types at once.

Why the reliefs care who signs the cheque

Both schemes give income tax relief to individuals, and HMRC’s guidance is explicit about it.

“The individual must make the subscription on his or her own behalf.”— HMRC Venture Capital Schemes Manual, VCM10520

Relief cannot be claimed by someone subscribing as a nominee or trustee, apart from a narrow exception where an individual uses a nominee and is treated as the subscriber. In practice the money should come from the investor’s personal account, not a business account.

A family investment company, a private limited company set up to hold family wealth, is not an individual, so it cannot claim SEIS or EIS relief on its own subscription. The same applies to a trust holding family money. HMRC also notes that investing through a partnership, including a limited partnership or LLP, does not give an individual relief, because the individual owns a share of the partnership’s assets and not the shares themselves.

That does not shut family office investors out. A family member can often invest personally and claim if they meet the conditions, while the single-family office or a family investment company might invest on ordinary commercial terms with no relief attached. Some families instead use a nominee structure, in which a fund manager subscribes for and holds the shares on behalf of each individual, who is treated as the investor for relief purposes.

If you are raising £300,000 and a family office investor offers to put in £150,000 through its holding company, that £150,000 would go in without relief, while the same amount subscribed personally by a family member who meets the conditions could qualify. Neither route is wrong, but they lead to different cap table entries and different paperwork, so your accountant should confirm which fits before any shares are issued.

The conditions that still apply to individual investors

Even when an individual subscribes personally, several conditions apply. The company must be a qualifying company, the shares must be new ordinary shares paid for in cash, and they must be held for a three-year holding period or the relief can be withdrawn. HMRC also applies a risk-to-capital condition, which looks for a genuine growth business and an investor who faces a real chance of losing money. An investor who asks for downside protection or a guaranteed exit could put the relief at risk.

The rules on a connected investor and associates deserve particular attention in a family setting. An investor with a substantial interest, meaning more than 30% of the shares, voting rights or rights to assets, is treated as connected and cannot claim income tax relief, and the holdings of associates such as a spouse, parents or children are counted together. A family that invests through several relatives can reach the 30% line collectively even if no single person does.

Limits, reliefs and the knowledge-intensive route

SEIS gives 50% income tax relief on up to £200,000 per investor per tax year, and the company can raise £250,000 in total, with gross assets under £350,000, under three years of trading and fewer than 25 employees. EIS gives 30% income tax relief on up to £1 million per investor per year. If your company qualifies for knowledge-intensive company EIS treatment, that investor limit rises to £2 million, provided at least £1 million goes into knowledge-intensive companies, which can suit wealthier family office investors who want to put more through personally.

Company-side limits also changed from 6 April 2026 under the Finance Act 2026. An EIS company can now raise up to £10 million a year, or £20 million on the knowledge-intensive company EIS route, with lifetime limits of £24 million and £40 million and gross assets tests of £30 million before and £35 million after the share issue. After the qualifying period, gains on the shares are generally covered by a capital gains tax exemption where income tax relief was given and not withdrawn. Deferral relief lets an investor who has recently sold an asset reinvest that gain in EIS shares and defer the tax until the EIS shares are sold.

Advance assurance and the paperwork

An advance assurance letter is HMRC’s non-binding view that your proposed share issue is likely to qualify. Most angels expect to see one before they commit, and family office investors who invest personally are likely to do the same. It covers the company and the planned issue, so each investor’s own circumstances still need checking separately.

After the shares are issued, the company files an EIS1 compliance statement (SEIS1 for SEIS). Once HMRC accepts it, the company issues the SEIS3/EIS3 certificate that each individual investor needs to make a claim. Without that certificate there is no claim, which is why the company’s paperwork matters as much as the investor’s status.

Also read: SEIS Advance Assurance: How to Get It and Why Deals Stall Without It

Mixed fundraises and the cap table

Many fundraises combine individuals claiming relief with family office investors who cannot, and that is workable as long as the cap table records who is subscribing, in what capacity and through which entity. It helps to ask early in whose name the shares will be issued and whether any relative is an associate whose holding pushes the group over the 30% line.

Also read: How to Find Angel Investors in the UK: Where the Money Actually Sits

Here are a few questions to take to your accountant

I. In whose name will each investor’s shares be issued: the family member personally, the single-family office or a family investment company?

II. Do the holdings of relatives and other associates add up to a substantial interest above 30%?

III. Does our company qualify for knowledge-intensive company EIS treatment, and does that change how much each investor can put in?

IV. Do we have advance assurance in place before we issue any shares?

The Autumn Budget on 28 October 2026 is the next point at which tax rules for wealth could move. We have not seen a confirmed change to these reliefs, but the position on the day you issue shares is what counts. 

What we would still like to understand is how family office investors respond as the wider tax picture for wealth evolves, and whether more of them will choose to invest personally or through a structure the reliefs were never designed around.

This guide is general information, not tax advice. Check your specific fundraise with a qualified accountant or tax adviser.

Sources:HMRC Venture Capital Schemes Manual (VCM10520, VCM16040, VCM16050, VCM37040); GOV.UK (venture capital schemes: tax relief for investors); Sifted (family offices explainer, December 2023); With Intelligence (London family office analysis, August 2025); PwC (Global Family Office Deals Study, five trends in startup investments); Saffery (EIS, SEIS, VCT reliefs explained); The Carry (SEIS and EIS limits for 2026); Philip Hare & Associates (EIS position at 6 April 2026); Kirk Rice (Family Investment Companies); SeedLegals (SEIS rules for investors); Grant Thornton (Autumn Budget 2026).