Hector Garcia, one of my favorite QuickBooks trainers and a real guru when it comes to both Desktop and Online versions, recently posted a link to this fantastic list of the items that do not import when you convert a file from QBDT to QBO.

A short list of the most common items is here, but there are many more that can mess up an otherwise perfectly good transfer, creating headaches and wasted time for all involved — so I recommend using the master list as a sort of checklist when 1) deciding whether the client may be a good match for conversion (because there are still a lot of features QBO doesn’t yet have that QBDT does); and then, 2) preparing for the conversion itself.

In my opinion, there are a lot of important items on the comprehensive list that are not listed on the “most common” items list, such as:

• The bank account number and notes are not converted.
• For accounts where the “detail type” is obvious (for example, Undeposited Funds), the conversion process assigns that detail type. For accounts where it isn’t clear what the detail type should be (the majority of accounts are like this), the conversion process assigns a generic detail type within the type, such as Other Miscellaneous Income which must be edited later. Run the Account Listing report (Reports/All Reports/Accountant Reports) post-conversion to review the Detail Types assigned. Drilling into the report brings you to the edit account window, where you can update the Detail type.
• The audit trail in QuickBooks Desktop is not converted to QuickBooks Online. This has been an issue for clients of mine before, so make sure not to get rid of the old file, just in case.
• All the vendors in the QuickBooks Desktop data file are converted to QuickBooks Online but not all of their detail/information converts. The address on the bill payment check is replaced by Vendor address in Vendor list; again, clients have had problems with this — if they’re not expecting it, then all-of-a-sudden, checks are going to the wrong place.
• Only Profit & Loss budget types convert to QuickBooks Online — no Balance Sheet budgets, which can put you out of compliance with some grants and agencies that require it.
• Your QuickBooks Desktop closing date is converted, but the password is not. This is a big one.
• After conversion, the Exceptions to Closing Date report in QuickBooks Online will no longer show the exceptions that you had accumulated — only new exceptions will be tracked.
• QuickBooks Online does not support custom fields on customers, vendors, employees, or items.
• Not all of the customer detail and job information for costing purposes is converted.
• Attachments on transactions are not converted. Another big one for some clients — make sure you keep the final Desktop file for future reference.
• QuickBooks Online currently doesn’t have group items.  If you have group items in your Desktop data file, they are not converted to the products & services list.
• If you have accounts, customers or vendors marked as inactive in your QuickBooks Desktop data file that have an open balance, they are converted to QuickBooks Online Plus as regular, “active” elements.
• You can’t export inventory from QuickBooks for Mac. Only QuickBooks Desktop for Windows can export inventory to QuickBooks Online.
• QuickBooks Online Plus tracks inventory using the First-in-First-out (FIFO) method in accrual only. When you select the option to import inventory it will ask you to choose a date, which we will use to recalculate your inventory based on FIFO calculations (Desktop uses average cost). Again, this can be a huge adjustment for some (even though it’s a more acceptable method of costing from an accounting perspective).
• You can’t make a journal entry billable in QuickBooks Online.
• None of the memorized reports are converted.
• You have to un-link and re-link your existing QuickBooks Merchant Service account to QuickBooks Online.
• User names and passwords from Quickbooks Desktop do not convert.  Existing users do not automatically have access to QuickBooks Online, instead they will need to be re-invited from QuickBooks Online to gain access. Furthermore, QuickBooks Online has access permissions that limit the user’s ability to see and use different parts of the application but they don’t allow you to control access at the level of transactions like Desktop can.
• Imported Purchase Orders that are closed will not be linked to their corresponding Bill.
• Past reconciliation reports are not converted to QuickBooks Online — yet another reason to keep a final copy of the old Desktop file.
• If you import to anything other than a Plus account you will not be able to see your recurring transactions; they’re there… but you can’t see them unless you upgrade to “Plus”. (Though for some reason, if you’re importing to QBO Simple Start, you actually have to delete all recurring transactions and templates from within Quickbooks Desktop before importing to avoid errors after importing.)
• Reminders do not convert to QuickBooks Online.
• Although your Accrual Basis reports will match in both products, your Cash Basis reports may not match (search the article for this phrase for examples) — it’s best practice to run an “all dates” accrual report in Desktop before converting and then the same report in QBO afterwards to make sure things are all good.
• After the conversion, there will be at least two sales tax payable accounts on the Chart of Accounts: one for each old Sales Tax Payable account from QuickBooks Desktop and one for each Sales Tax Agency Payable account in the new QuickBooks Online (set up automatically for each jurisdiction during the conversion). Moving forward, QuickBooks Online will only use the new Sales Tax Agency Payable account, and all sales tax will be managed from the Sales Tax Center.

There’s more, but those are the ones I’ve found can cause issues most often. Make sure to read the whole list — What doesn’t come over during an import from QuickBooks Desktop … – QuickBooks Learn & Support — and consider using it as a checklist before and after conversion.