With the introduction of the Employment Allowance last year, and the personal allowance increasing to £10600 on 6.4.15, the optimal salary for 2015/16 where the director has no other income will be £10600. Athough this will result in the director paying some employees N.I (12% of £10600-£8060 = £304.80), his corporation tax bill is reduced by £508 (20% of £10600-£8060). The employers N.I. (13.8% of £10600-£8112 = £343.34) will be fully cancelled by the Employment Allowance which is up to £2000.
Net dividends of no more than £28606 for the year will keep the director inside the 40% tax threshold. Net dividends of £28606 = gross dividends of £31784. Adding in the salary of £10600 gives gross income of £42384. The 40% tax threshold for 2015/16 is £42385.