October 31st to offset it against the previous tax year's earnings. So to set it against 2006 earnings you have until October 31st 2007. You missed the October 31st 2006 deadline for offsetting against 2005 earnings.
What sort of pension - e.g. personal, executive, PRSA, occupational other? For all but occupational schemes I think that the total contributions matter but for occupational schemes it's just the personal/AVC contributions that matter in relation to the tax relief limit. I could be wrong!
In an occupational/Executive scheme, gross earnings are your total earnings, including overtime, bonus, BIK, medical insurance, basically anything you pay tax on you can claim relief up to the relevant limits. It does not include the employer contribution since it is not taxable in your hands.