is a csv file saved as OpenOffice Calc able to be imported into QB online

I appreciate your effort in writing your concern here in the Community, Zoomcrank. Let’s work together to establish a streamlined and effective process for importing your invoices in QuickBooks Online.

QuickBooks Online imports invoices that contain either single or multiple line items. This flexibility allows you to represent invoices that may include various products, services and charges all on a single invoice.

To properly organize them in OpenOffice Calc, save them in CSV format, limit each batch to a maximum of 100 invoices, and ensure the total number of rows does not exceed 1,000.

Please ensure to configure the columns and rows based on the guidelines established by QBO. I've attached this sample file and fill in the required columns for a seamless importing process:

After that, save your document in CSV format. click on File, then select Save As, and opt for Text CSV or (.csv) as the desired file type.

If you require a file converter, consider seeking a third-party application that can facilitate the conversion of files to CSV format. Visit this page: QuickBooks App Center.

In addition, here's an article that provides answers to common inquiries about data import in QBO: Common questions about importing data to QuickBooks Online.

Moreover, I encourage you to take advantage of our QuickBooks Live Expert Assisted service to elevate your QBO experience. Our proficient team of specialists is on hand to offer quick support that meets your business needs. They will guide you in understanding and managing your accounts, invoices, customers, and vendors.

I am here to provide you with any additional help you may need concerning your invoices or other data imports in QuickBooks Online. Please leave a comment below, and I will be glad to assist.

@Zoomcrank 

You can try an importer tool as a workaround.

https://get.transactionpro.com/qbo

Otherwise, you can purchase a 3rd party service to migrate your data.

Thank you for your reply. After hours and hours of doing my very best to rectify every potential fault discoverable on my zoho Spreadsheet containing the first 100 invoices exported from Invoice2Go to my Downloads folder, having removed all the email addresses attached to my my Invoices since QBO doesn't want to accept them, and having re-written every description so that it only occupies a single line on the spreadsheet, I have finally arrived at a single error from QBO which has me utterly dumbfounded: 

Some rows need invoice numbers

When an invoice has multiple rows, enter the same invoice number in every row that's part of that invoice.

This seems ludicrous. There aren't any multiple rows. Everything has been simplified to occupy no more than a single line as I have mentioned already. The only potential reason I can think of is the somewhere between 10 and 20 missing invoices which went went badly for me back then, and so for example Invoice 1 and 2 are simply missing, but that's because I simply used the next Invoice available instead. I originally tried to include the missing invoices by giving them a "Void" text in the Name column, but QBO wasn't having anything in the Amount columns that either stated N/A or 0 for GBP value. So I ended up removing them.

I'm slowly losing the will to live on this project. QBO is unbelievably inflexible, or so it would appear...