The Seisly blog

SEIS, EIS and HMRC advance assurance

Writing on SEIS and EIS advance assurance: what HMRC looks for, how to prepare an application, and honest comparisons of the ways to file.

Latest

25 July 2026

What the Seisly blog covers

What we write about here: SEIS and EIS advance assurance, what HMRC looks for, and how to prepare an application that reads the way HMRC expects.

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Essential reading

Lead piece

The SEIS & EIS Playbook

The nine tests HMRC applies, the language behind rejections and approvals, and a fully worked annotated application.

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Comparison

Seisly vs SeedLegals

Price, scope and turnaround compared, honestly, against SeedLegals’ plan-plus-add-on model.

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Comparison

Seisly vs FounderCatalyst

How the two compare when FounderCatalyst bundles advance assurance into an annual plan.

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Pitch decks

The five slides that get applications refused

Where applications fail on language, what HMRC reads for, and the qualifying substitution.

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