You can claim SEIS tax relief within five years from 31 January following the tax year in which you made your investment. This date aligns with the deadline for Self Assessment tax returns.

If you do not fully utilise your SEIS allowance of £200,000 per year, you cannot roll over the unused portion to the next year. However, you may carry back SEIS tax relief to the previous tax year, provided you have not already reached the maximum investment limit for that year.

Important: For personalised advice suited to your individual situation, be sure to consult a qualified tax professional.