Entering 4 digits of account number in the format sheet can be accepted?

It's a pleasure to have you here today, Fiona. I'll answer your question about importing spreadsheet file format to your Chart of accounts inside QuickBooks Online (QBO).

In QBO, you can enter 4 to 5-digit numbers in the Account Number column inside the spreadsheet and import them successfully into your Chart of Accounts. Also, you'll want to map the spreadsheet fields accurately to avoid errors during the process and have the data available inside your company file. 

For further guidelines, you can check this article: Import your chart of accounts to QuickBooks Online.

Moreover, we recommend checking these articles in case you want to upload bank transactions inside QBO:

• Format CSV files in Excel to get bank transactions into QuickBooks
• Categorise online bank transactions in QuickBooks Online

We look forward to helping you again if you have other questions about the program or need further assistance getting data into your account. Feel free to comment below so we can respond right away. Keep safe.