Foreign salary taxation

During FY 2015-16, Mr. A (Employee) received Salary for all 12 months in India. His Company send him to Abroad during November 2015. There he received 5 months Salary & paid taxed to that Foreign Govt. (Upto 31.03.2016). So, totally he earned 17 Salaries but Form 16 issued by employer contains only Indian Income & employer forgot to calculate Tax as per DTAA provisions. (Employee returned to India in FY 2016-17). Our query is while filing IT Return for FY 2015-16,if we include 17 salaries, Mr.A will end-up paying high tax & interest in India. To avoid this, can we file IT Return with 12 Indian Salaries & 2 Foreign Salaries? Foreign Salary of Jan-Mar 2016 can we shift to FY 2016-17? FY in India is Apr-Mar FY in Abroad is Jan-Dec Is there any provision which facilitate this? Pls mention any Case Laws to support this...