Contribution to Delhi Govt. Health Scheme is eligible for deduction u/s 80D in relation to the Assessment Year 2014-2015 and subsequent Assessment Years.
If you contribute in the current financial year (i.e. 13-14), you will get deduction (upto the limit as prescribed in section 80D) at the time of computation of income in the next year (i.e. Assessment Year 2014-2015.)
Infact, Finance bill 2013 proposed to expand the scope of section 80D in the following manner:
'In section 80D of the Income-tax Act, in sub-section (2), in clause (a), after the words "Central Government Health Scheme", the words "or such other scheme as may be notified by the Central Government in this behalf" shall be inserted with effect from the 1st day of April, 2014.'