Tabbing In lets you to type a Tab to go to first field on a new window to speed entry.
Big Business 14 updated all data entry windows and some are still missing this feature. For example, Big Business 14.69 fixes the Misc. Posting window to allow Tabbing In.
Big Business is designed to allow full keyboard operation. Tab works to move forward though fields, change the Sort column in Listing, and Shift-Tab works to go backwards.