Investor Tax Certificates (SEIS3 / EIS3)
for SEIS founders

The SEIS3 and EIS3 are the certificates that turn an investor's share subscription into actual tax relief. They are issued by HMRC to the company after SEIS1 or EIS1 approval and forwarded by the company to each investor. Without the SEIS3 in hand, an investor cannot claim 50 percent SEIS income tax relief or 30 percent EIS income tax relief on their personal tax return.

The administrative work of distributing certificates is small but the operational stakes are high. Investors expect their certificates within weeks of HMRC approval, particularly investors who want to use the carry-back election to claim relief against the previous tax year. Founders who let the certificates sit in a drawer for months damage investor relationships and lose follow-on capital.

Specialist accountants in our network handle the certificate distribution as part of the SEIS1 or EIS1 engagement: certificate batches received from HMRC, individual SEIS3 or EIS3 forwarded to each investor with covering communication explaining the relief-claiming process, scanned PDF copies retained for the company file, and replacement certificates obtained from HMRC if any are lost.

The SEIS3 and EIS3 are pre-numbered HMRC-issued certificates that come to the company in a batch after the SEIS1 or EIS1 is approved. Each certificate carries a unique reference number, the company name and registered office, the investor name and address, the date the qualifying shares were issued, the number of shares, the amount subscribed, and the relief percentage (50 percent for SEIS, 30 percent for EIS). The investor uses the certificate as the formal evidence on their self-assessment return that the qualifying investment took place.

The mechanics of claiming relief are straightforward at the investor end. The investor enters the SEIS or EIS investment details on the additional information schedule SA101 of their self-assessment return, ticking the SEIS or EIS box and recording each certificate's unique reference number. The relief is set against income tax liability for the year of the investment, with the option to elect to carry the relief back to the immediately previous tax year if the investor's personal tax circumstances make that advantageous (typically because the previous year's income was higher and the marginal rate was higher).

The carry-back election is the moment when timing on certificate distribution becomes critical. The election is made on the self-assessment return, and the return for the previous tax year has to be filed (or amended) inside the relevant filing window. For an investor who wants to carry back relief on a SEIS investment made in March of tax year 2026/27 to tax year 2025/26, the previous-year self-assessment has to be filed or amended by 31 January 2027 with the SEIS3 in hand. A founder who waits until April 2027 to distribute the certificate has effectively cost the investor a year of cash flow on the relief, even though the relief is still available.

Where the investor has lost the SEIS3 before claiming relief, HMRC will issue a duplicate certificate on request from the company. The accountant submits a duplicate-certificate request to HMRC's Venture Capital Reliefs team explaining the circumstances, and HMRC issues the replacement to the company for forwarding to the investor. The duplicate carries the same reference number as the original. Where the investor has already claimed relief and just lost the paper certificate, HMRC will typically not issue a duplicate because the original claim is on file and a replacement serves no purpose.

Overseas investors claiming UK tax relief on SEIS or EIS shares face additional complexity that is worth flagging at the certificate distribution stage. UK income tax relief on SEIS or EIS is available only to investors who have UK income tax liability to set the relief against. A non-UK-resident investor with no UK income tax liability has no relief to claim, even though they hold a valid SEIS3. UK tax residents with overseas employment income can usually claim, depending on the residency and remittance basis position. The accountant typically includes a brief note in the covering communication for overseas investors explaining the limitation, so the investor is not surprised by their accountant later.

Crowdcube and Seedrs syndicate rounds produce SEIS3 distribution at scale: a single round can have 50, 100, or even 200 underlying investors with individual certificates. The platforms handle the bulk-distribution process for their own rounds, but founders raising on the platforms still own the relationship with each investor and benefit from a covering communication that extends beyond the platform's standard email. A specialist accountant prepares a covering note that the platform can attach to the bulk distribution, explaining the relief mechanics in plain English.

Investors who hold SEIS or EIS shares through a SIPP (Self-Invested Personal Pension) have a different relief structure: the SIPP itself is a tax-exempt wrapper, so income tax relief on the SEIS investment is not available. The SEIS3 is still issued to the SIPP as the legal owner of the shares, but the underlying SIPP investor cannot claim income tax relief in the conventional way. The SEIS investment in a SIPP is generally driven by other tax considerations (the gains inside the wrapper are tax-free regardless), and the certificate distribution process is the same in form but the relief claim is mechanically different. The accountant flags the SIPP-investor situation in the covering communication.

Investors who claimed SEIS or EIS relief on the previous-year return (by carry-back) and who later have HMRC enquire into the carry-back claim need supporting evidence of the certificate's authenticity and the company's continuing qualification. The company file copy of the SEIS3 PDF, alongside a confirmation from the company that the qualifying conditions remained satisfied through the relevant period, is what HMRC typically accepts. Specialist accountants retain these records as part of the standard engagement so the evidence is available when needed.

Where the company is acquired or restructured between SEIS3 issue and the end of the three-year qualifying period, the certificates remain valid evidence of the original SEIS investment, but the underlying shares may have been exchanged for new shares in the acquirer (in a qualifying share-for-share rollover) or extinguished (in a non-qualifying acquisition triggering clawback). The accountant maintains the link between the original certificates and the post-transaction position so investors and HMRC can both follow the chain.