https://help.tallysolutions.com/docs/te9rel64/Voucher_Entry/Optional_Non-Accounting_Vouchers/Optional_Non_Accounting_vch_TallyERP.htm

Introduction to Optional and Non Accounting Vouchers in Tally.ERP 9

Non-accounting/unconventional vouchers are the special vouchers that are used to record provisional or non-accounting transactions. Unconventional vouchers are mainly used to exclude unnecessary entries or provisional entries from the books of accounts and make them available for what if (future reports, projections, forecasts, and so on) reports required at any given time.

See also

Memorandum Voucher

Optional Vouchers

Reversing Journals

Post Dated Vouchers