For Form 16 Time limit:By 31st day of May of the financial year immediately following the financial year in which the income was paid and tax deducted
For FY 2010-11,Certificate should be given by 31.05.2011
For Form 16A
Time Limit:Quarterly,Within fifteen days from the due date for furnishing the statement of tax deducted at source under rule 31A.Yearly Forms can not be issued in any case.
For q4 (1/2011 to 3/2011) due date is 30.05.2011 Consequences Form 16 & 16A Penalty for Failure to issue Form 16 & 16A(section 272A):Employer shall be liable for a penalty at the rate of 100 for every day during which failure continues,if delay is without reasonable cause.Total penalty under section 272A,200(3),203,206,should not exceed the amount of tax deductible at source.