Per the IRS Instructions for Form 4684 Casualties and Thefts, page 6:
Losses From Ponzi-Type Investment Schemes
The IRS has issued the following guidance to assist taxpayers who are victims of losses from Ponzi-type investment schemes.
If you qualify to use Revenue Procedure 2009-20, as modified by Revenue Procedure 2011-58, and choose to follow the procedures in the guidance, first fill out Section C to determine the amount to enter on Section B, line 28. Skip lines 19 to 27. Section C of Form 4684 replaces Appendix A in Revenue Procedure 2009-20. You don't need to complete Appendix A.
For more information, see the instructions for Section C later and the above revenue ruling and revenue procedures.
If you choose not to use the procedures in Revenue Procedure 2009-20, you may claim your theft loss by filling out Section B, lines 19 to 39, as appropriate.
To enter these losses in TaxAct®: