Section 89 relief to family pension received in arrears

Rebate u/s. 89(1) can also be availed for family pension. Read Rule 21A as extracted below: 

21A. 31[(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—

for details refer: https://incometaxindia.gov.in/Rules/Income-Tax