Our bookkeeping systems simultaneously track contributions for the purpose of donor recognition and documentation for tax deductibility, as well as for comparison from year to year for the organization. If donors pre-pay a pledge for a future year, or complete a pledge for a prior year, this can skew an organization’s reporting and analysis of their contributions. This is easily remedied by procedures that incorporate donor intent into the regular bookkeeping. For an example of the crucial difference this can make, see pages 59-63 of the Church Finance Handbook.
A detailed explanation of how to book these contributions is included here: Contributions Prepaid and Postpaid