In the event that your investment was eligible for EIS/SEIS tax relief when you initially invested, and you are selling your shares within three years of purchasing them, then you will lose the tax relief. This could mean paying back income tax relief to HMRC and losing your eligibility for capital gains tax relief.
Please note that all tax treatment depends on individual circumstances and is subject to change. We strongly advise anyone who is looking to sell shares that are eligible for tax relief to consult a professional tax advisor.