Donors must deliver checks on or by December 31 in order to claim a charitable contribution deduction for 2011. Checks that are placed in the church offering during the first worship service in 2012 will not qualify for a charitable contribution deduction in 2011, even if the check is predated to 2011 or was actually written in 2011. However, checks that are written, mailed, and postmarked in 2011 will be deductible in 2011 though they are not received by a church until 2012.