Rather than copying and pasting large amounts of data from a Microsoft Excel worksheet into QuickBooks, use QuickBooks' Import option. You will have to map the worksheet columns to the appropriate QuickBook headings, but the process should only take a minute or two. QuickBooks gives you a preview of the mappings you selected before finishing the import process.
Save your Excel file or spreadsheet in XLS or XLSX file format or extension.
Open your QuickBooks data file.
Make a backup of your data so that you would not lose important data should the import doesn't work properly. This is best practice each time you work on any data.
Click the QuickBooks "File" menu, select "Utilities," then "Import" and then "Excel Files."
Select your XLS file. Select the "Choose a sheet in this Excel workbook" drop-down menu and select "Accounts."
Click the "Mappings" button. Type a mapping name such as "Map QB Headers to XLS Columns." Click "Import Type" and select "Account." Select the blank row beneath the Import Data column heading to see all of the Excel file columns.
Click on the names to choose the fields you wish your data to be imported into. A pull-down menu will appear beside each name under the "Import Data" column where you will choose the Excel column designation where the data resides in Excel. Click "Save." At this point, you are back to the "Import a File" window.
Go to the "Preferences" tab and choose the applicable options to your import. Use the "Preview" option to ensure your Excel columns have been mapped correctly to QuickBooks.
Click on "Import" when everything looks fine.
Some versions of QuickBooks have wizards that make importing of files more manageable with a more stringent error-checking system. To import Excel files using the wizard, they should be in XLSM format.
For older versions of QuickBooks, you can covert the Excel files into IIF (Intuit Interchange Format), which can be a complicated process. IIF is a tab-delimited text file format used to import lists and transactions into QuickBooks. There are certain IIF Tool Kits available in the market to help with the process. Another disadvantage of using this import process is that error-checking is very minimal, so you are prone to make mistakes.
The process is irreversible; make sure to make a copy or backup of your files before proceeding with the import.