What are the basic eligibility requirements for SEISS?
SEISS is available if you are an individual, but for this purpose “individual” includes partnerships. It does not apply to you as an owner-manager of a small business operating as a company - it applies to you only if you are a self-employed individual who carries on a trade and if you have lost trading profits due to Covid-19.
The initial period of SEISS (up to 31 August 2020) provided for a grant to be available whether or not you continued to trade during the period for which payments are made, but you must have had an intention to trade in 2020/1. However, for a grant to be payable under the rules for the extension period of SEISS (from 1 November 2020 to 30 April 2021), you must be currently trading.
If your annual profits exceed £50,000 per annum, you are not eligible for any amount at all under SEISS. If half or more of your total annual income is not derived from your self-employment, you are not eligible for any amount at all under SEISS.
SEISS is available to an individual who has delivered a tax return to HMRC for the relevant tax years, i.e. 2016-17, 2017-18 and 2018-19, in which he has traded. This is not entirely clear since the Scheme appears to require a tax return to have been filed only for 2018-9 in that case. The individual must also have carried on a trade in the tax years 2018-19 and 2019-20.