This point cannot be made strongly enough: you must keep clear and thorough records when paying alimony or when receiving alimony payments.  Problems will definitely arise in the event that there is an additional spousal dispute or IRS challenge and you cannot provide adequate documentation. 

Suggested records the payer should keep:

• - Lists indicating each payment (date, check number, place where sent)
• - The original checks used for payments (these should be kept in safe deposit box or some other safe place).  Checks should be marked with the month for which the support payment is being made. 
• - The receipts signed by the recipient, if you pay in cash.

These should be kept for at least three years from the time you file the tax return, deducting the payments.

Suggested record the recipient should keep:

-Lists indicating when each payments was received, including:

• 1) The date payment was received
• 2) The amount received
• 3) The check number or other identifying document (such as the number of the money order)
• 4) The account number on which any check is written
• 5) The name of bank on which check is drawn or money order issued
• 6)  A photocopy of the check or money order
• 7) A copy of any signed receipt you give for cash payments.