Busy and Marg each export differently, and neither writes a single file that carries everything the way a Zoho or Odoo backup does — expect to bring masters and reports across as separate files.
Busy
Administration → Data Export Import → Export Data → Masters (Accounts, Items) → Excel. On Standard and Enterprise, the same screen can export XML too, when your version supports it. Basic exports Excel by report only — there is no XML option on that edition.
Marg
Reports → Management Report → Utilities → Data Import/Export → Tally/Busy Export writes ledgers, items and vouchers as two Tally-format XML files (a Masters file, then a Daybook file) — drop them on the same Pick screen and they are read like Tally's own Day Book. This is a different screen from ERP Bridger, which is Marg's own Marg-to-Marg transfer tool and does not write Tally-format files. Without the Tally bridge: Bridger → Export → Masters (ledgers, items) as CSV, then Reports → each report → Excel, and map the columns on the next screen.
For batch numbers and expiry dates on your stock, bring across Stocks → Current Stock's batch-wise report as Excel too - the Tally export only carries a batch's name, not its manufacturing or expiry date.
What comes across today
Parties, items, your chart of accounts with opening balances, invoices, bills, payments and journals — from whichever export you bring. Stock movements keep their batch number, and manufacturing/expiry date when you bring the batch-wise report, so they show up in your batch and near-expiry reports.
What is deliberately not copied
Filed GST returns, IRNs and e-way bills stay with the portal that issued them. Bank-statement matches and attached files are not copied either. Busy's own print formats and user rights stay in Busy; Marg's scheme masters and rate lists stay in Marg.
After you drop the file
Same five screens as every other source — matching columns, a dry run with a verdict on every record, then Import and Reconcile. The mechanics (and how undo and re-imports work) are in Import your data from Zoho, Odoo, Vyapar or a spreadsheet. Back to the full list of sources.