SEIS: income tax relief: withdrawal or reduction of relief: procedure: withdrawing relief
SEIS relief cannot be withdrawn via self-assessment. Instead it should be recovered by the making of a manual Special Assessment using SEES, and the charge entered onto SAFE.
Instructions on how to do this are at SAM22001 to SAM22030 following the same procedure as would apply for a withdrawal of EIS relief.
Where the shares in question were acquired from a spouse or civil partner, the assessment will be on the person they were transferred to.