Shares are assigned in terms of number, not in percentage. However, for your easiness, you may want to assign shares in such numbers that reflect the percentage. In that case, issue number of shares to each shareholder in such a number, so that the total number of shares becomes 100. Total share is calculated by adding up each shareholder's share number. Example: your share is 60, your spouse's share is 40. Then total shares = 60 + 40 = 100. In this case, you hold 60% and spouse holds 40%.