(1)Where, by reason of any portion of an assessee's salary being paid in arrears or in advance or, by reason of any portion of family pension received by an assessee being paid in arrears or, by reason of his having received in any one financial year salary for more than twelve months or a payment which under the provisions of clause (3) of section 17 is a profit in lieu of salary, his income is assessed at a rate higher than that at which it would otherwise have been assessed, the relief to be granted under sub-section (1) of section 89 shall be-(a)where any portion of the assessee's salary is received in arrears or in advance or, any portion of family pension is received by an assessee in arrears, in accordance with the provisions of sub-rule (2);(b)where the payment is in the nature of gratuity in respect of past services of the assessee extending over a period of not less than five years, in accordance with the provisions of sub-rule (3);(c)where the payment is in the nature of compensation received by the assessee from his employer or former employer at or in connection with the termination of his employment after continuous service for not less than three years and where the unexpired portion of his term of employment is also not less than three years, in accordance with the provisions of sub-rule (4);(d)where the payment is in commutation of pension, in accordance with the provisions of sub-rule (5); and(e)where the payment is not in the nature of salary paid in arrears or in advance or gratuity in respect of past services or compensation received at or in connection with the termination of employment or in commutation of pension, in accordance with the provisions of sub-rule (6).