If the accounting system behind your company in Fathom changes (eg. from Excel to a cloud based system, or from MYOB to Xero), we recommend you delete the old company in Fathom and import again from the new system.
It's not possible to merge two files from differing sources in Fathom, however if it is a requirement to retain historical data for reporting and combine it with the new source, there is a workaround using consolidated groups.
The approach is to leave the old company in place and have it finish at a certain month (eg. June). The new company should be imported starting from the next month (eg. July). Then create a consolidated group that combines the two companies.
There a few things to take note of when using this approach:
Retaining both companies will mean an additional cost for the second company. Consolidated groups in Fathom are free of charge.
In each company you should use KPIs sourced from the KPI Library so that they flow up to the consolidated group.
Balance Sheet Carry-forward
In a normal consolidation, companies that finish before the consolidated group finish date will have their balance sheet 'carried forward'. Results from the last period in the company are copied into any future empty periods.
When combining data for the same company this is unhelpful and will result in an incorrect balance sheet.
This can be solved by adding one more period to the old company and 'zeroing' out the balance sheet, or you could add an Excel elimination company to perform the zeroing out as an alternative.
You wish to merge a new Xero file with your old Excel file that contains historical data.
The Excel file contains data from Jul 2016 - Jun 2019. The Xero file has data from Jul 2019 - Jun 2020.
The 'Cash & Equivalents' in the Excel balance sheet at Jun 2019 is $1,000,000.
'Cash & Equivalents' in the Xero balance sheet at Jun 2020 is $1,500,000.
When viewing results in Fathom for Jun 2020 in the merged group, 'Cash & Equivalents' will show $2,500,000. This is because the balance sheet of the Excel file is being carried forward to later periods.
To fix this, modify the Excel import to include a column for 'Jul 2019'. Input '0' as the value of all accounts.
Now, the value of '0' will be carried forward, and your Balance sheet will display the correct value going forward.