An S corporation shareholder's basis is significant because:
The adjusted basis of the shareholder's stock for purposes of computing the limitation on the amount of the S corporation's losses he can deduct (the loss limitation) is computed after the basis is reduced by the year's nontaxable distributions made to the shareholder. IRC Sec. 1366(d).
The adjusted basis of the shareholder's stock for determining the tax effects of the S corporation distributions to him is determined by increasing the basis for his share of the S corporation's income items for the year, but without decreasing the basis for his share of the S corporation's losses for the year. IRC Sec. 1368.
3.26 Ark. Code R. 51-409(c)(1)