Investors within an SPV can hold fractional shares however they cannot claim S/EIS tax relief on the fractional shares.
If investors own fractional shares then EIS eligible shares have to be rounded down to 0 decimal places. This can make the final investment amount different from the claimable relief amount in an SEIS3 form.
We often come across discrepancies between shares owned and shares eligible for relief- it is simply due to the inability to claim fractional shares.
Tax relief claimable is the figure on EIS3 forms, not the final investment amount.