For the overwhelming majority of UK angels, "tax reporting" means one document: the Self Assessment return. It's the channel through which you claim your reliefs, declare your gains, and book your losses. Get the return right and HMRC needs nothing else from you. Get the supporting paperwork wrong - a missing certificate, a reference left blank - and the relief you were counting on simply doesn't land.
So the real question isn't "what does HMRC want" in the abstract. It's: which boxes, which numbers, and by when. Let's take it in order.
Do you even need to file a return?
Writing an angel cheque doesn't, by itself, oblige you to file. You file because you have something to report or something to claim. For an active angel, that "something" almost always shows up: you want the SEIS or EIS income tax relief, you've crystallised a capital gain, or a portfolio company has failed and you're claiming loss relief. Any one of those means a return.
If you've never filed before, you have to register with HMRC first, and the deadline to register for a given tax year is 5 October after that year ends. Leave it later and you're into penalty territory before you've claimed a thing. The practical move is to register the moment you know you'll have something to report.
SEIS and EIS: the certificate comes first
This is where most of the value - and most of the friction - sits. Before you can claim a penny of SEIS or EIS income tax relief, the company has to send you a compliance certificate: an SEIS3 for the Seed Enterprise Investment Scheme, an EIS3 for the larger Enterprise Investment Scheme. The certificate confirms HMRC has authorised the company to treat your shares as qualifying, and it carries the unique investment reference you'll type onto your return. No certificate, no claim. It's worth repeating because it catches people out every January.
The headline reliefs are generous, which is the whole point of the schemes. Under SEIS you get income tax relief at 50% of what you invest, on up to £200,000 a tax year. Under EIS the rate is 30%, on up to £1,000,000 a year - or up to £2,000,000 if at least £1,000,000 of it goes into knowledge-intensive companies. Both schemes let you carry the relief back to the previous tax year, which matters when last year's income tax bill was the bigger one. And both require you to hold the shares for a minimum of three years; sell early and the relief is clawed back.
On the return itself, the claim goes in the "Other tax reliefs" section of the additional information pages (form SA101), or the equivalent screen if you file online. You enter the company name, the amount subscribed, the date of issue, and the reference from the certificate. If you're carrying relief back, you say so on the same claim and state the amount. HMRC's own helpsheets - HS393 for SEIS and HS297 for EIS - walk through the exact entries.
The relief is generous, but it's not automatic. HMRC won't chase you to claim it.
One point of order that trips up first-timers: the certificate usually arrives months after you invest, because the company can't apply for the authority to issue it until it has been trading for a while or has spent most of the round. Invest in January, still waiting in the autumn - that's normal, not a warning sign. You have a long window to claim: up to five years after the 31 January following the tax year of the share issue.
VCTs report a little differently
If part of your early-stage exposure runs through a Venture Capital Trust - a listed fund that invests in qualifying small companies - the reporting shape changes. You claim income tax relief at 20% on what you subscribe, up to £200,000 a tax year, again through Self Assessment. The catch is a longer leash: you must hold the VCT shares for at least five years for that relief to stick.
The upside is that VCTs are light on ongoing reporting. Dividends from a qualifying VCT, within the annual limit, are tax-free, so there's nothing to declare on them. Gains on VCT shares are free of capital gains tax too. The one thing to know going in: there is no loss relief on a VCT, unlike SEIS and EIS. HMRC's HS298 helpsheet covers the detail.
Capital gains, deferral and exemption
Gains are the other half of what HMRC wants to see. If you sell shares and the total gain for the year is above the annual exempt amount, it goes on the capital gains pages of your return. But the venture schemes carry valuable wrinkles here.
Shares held under SEIS or EIS for three or more years are exempt from capital gains tax on disposal, provided you received income tax relief and it hasn't been withdrawn. SEIS also offers reinvestment relief: you can exempt 50% of a gain you reinvest into SEIS shares, on up to £100,000 of investment a year. EIS instead offers deferral relief, letting you postpone an existing gain by rolling it into qualifying EIS shares - the gain comes back into charge later rather than disappearing. These are reported through the same capital gains pages, with the relevant boxes flagged.
When a company fails: loss relief
Early-stage portfolios lose money on individual names - that's the arithmetic of the asset class. When a SEIS or EIS company goes under, loss relief can take some of the sting out, and it's claimed on the same return. The loss is calculated net of the income tax relief you already had, and you can usually set it against either income or capital gains, depending on what works for your position. Again, VCTs are the exception - no loss relief there.
A note on the company's side of the line
Worth keeping straight: the reliefs you claim depend on the company having qualified, but the company's eligibility tests are its problem, settled before you invest. For context, an EIS company generally must have gross assets no greater than £30 million before the share issue (and no more than £35 million immediately after), fewer than 250 full-time-equivalent employees, be within seven years of its first commercial sale, and stay within annual and lifetime raise limits - currently £10 million a year and £24 million over its life, with higher ceilings for knowledge-intensive companies. These figures are set by HMRC and have moved over time, so check the current gov.uk EIS guidance rather than relying on memory. By the time a certificate reaches you, that work is done - your job is the return.
The dates that actually bite
Three to commit to memory. 5 October after the tax year ends: the deadline to register for Self Assessment if you're new to it. 31 October: the deadline if - unusually - you still file on paper. 31 January: the deadline to file online and to pay any tax due. Miss the filing date and there's an automatic £100 penalty even if you owe nothing; miss the payment date and interest starts running. The reliefs are worth real money, but none of it helps if the return is late.
That's the shape of it. Keep your SEIS3s and EIS3s somewhere you can find them, log your gains and losses as they happen rather than reconstructing the year every January, and the return becomes data-entry rather than archaeology. And to say it plainly: this is general editorial information, not financial or tax advice. The reliefs are valuable but the rules have sharp edges, and a wrong claim is your liability. Run anything material past an accountant or an FCA-regulated adviser before you file.