Taxation of Businesses Income from sole proprietorships and flow-through entities is taxed once at the individual owner level while corporate income is taxed twice once at the corporate level and again at the shareholder level upon dividend distributions or stock salesTaxation Of Businesses • Income from sole proprietorships and flow-through entities – is taxed once at the individual owner level while corporate income is taxed twice, – once at the corporate level – and again at the shareholder level upon dividend distributions or stock sales