Still making invoices in Excel or Word? When to switch, and how

Almost every business starts with invoices in Excel, Word, Google Sheets or a free template from the internet. You copy last month's file, change the name and the amount, and save it as a PDF. It costs nothing and it works, for a while. The trouble is that the file only makes the invoice. It does not keep count, check the tax or remember who has paid. You do all of that in your head.

Honest signs it is time to switch

If two or more of these sound familiar, your spreadsheet is costing you more than it saves.

• Numbering mistakes. Two invoices with the same number, or a gap because a file was deleted. In many countries the rules expect invoice numbers to be unique and in order, and a tax office can ask about a missing one.
• Tax errors. A formula copied one row too far, the wrong VAT or sales tax rate, or in India CGST and SGST charged to a customer in another state who should have been charged IGST. Small slips like these can hold up your customer's tax claim, and then your payment.
• No idea who owes you. To answer “how much is unpaid?” you open ten files and your bank app.
• Chasing by memory. You remind people when you happen to remember, and sometimes you remind someone who already paid.
• Tax returns by hand. Each month or quarter, you or your accountant type every invoice again into a sheet to work out the VAT, GST or sales tax you owe.

If you send three invoices a month, charge no tax and get paid on time, a spreadsheet may be all you need. That is fine. Switch when the list above starts to hurt, not before.

What you gain

An invoicing app does the counting for you. Numbers run in order on their own. Tax is worked out from your country and your customer's details, so the right rate appears without a formula. Each invoice has a status (Draft, Due, Overdue, Part paid, Paid), so the list of who owes you is always there. And the tax totals your accountant needs come from the same invoices, with nothing typed twice. If you are unsure what a correct invoice must show, our checklist on what every invoice must show covers VAT, GST and sales tax.

What switching involves

Numbering: start fresh, or carry on

Your old invoices stay in your old files. The new app does not need them, and Openn Invoice does not bring old invoices in. What matters is that your new numbers never clash with the old ones.

In Openn Invoice you set your own prefix, up to four letters or digits, like HP. Numbers then run in a fresh series for each financial year of your country: HP/26-27/0001 for a UK business whose year starts in April, DS/2026/0001 where the year follows the calendar. In India the series restarts on 1 April, as GST expects. That gives you two clean ways to switch:

• At the start of your financial year. The new series starts at 0001, which is what you would do anyway.
• Mid-year. Pick a prefix your old invoices never used. Your old numbers and the new ones can never be the same, so nothing repeats in the year.

Rules on numbering differ by country, so if you are not sure which suits your books, ask your accountant before you send the first new invoice.

Bring in your customers and items from a CSV file

You do not need to type your customer list again. Save it as a CSV file (a plain table that almost every program can read and write) and upload it. The same goes for your items or services, with their rates and tax.

• Excel or Google Sheets: open the list, then File, Save As (or Download), and choose CSV.
• Word: if your customers only live inside old invoices, copy the names into a sheet first. It is a one-time job.
• Your accounting app: most have an export option on the customer or item list. In India that includes Tally, Vyapar and myBillBook. If it gives you an Excel file, open it and save it as CSV. Menu names differ, so look for “Export”.

Column names do not need to match exactly: Name, Customer Name and Customer all work. Only the name is required. If a customer with the same name already exists, that row is skipped, never replaced. There is a template for your country on the Import page if you want to start from one.

Name,Tax ID,Email
Northwind Inc,,ap@northwind.example
Atelier Klein,DE123456789,
Brew Street Cafe,,

A first-week plan

Day 4 is the one people skip. Your old files know who owes you money today. Do not make those invoices again in the new app: the same sale would then have two invoices with two numbers. For a few weeks you look at both lists. After that, the old one is empty.

Keep your old files

Do not delete your old invoices once you switch. Tax rules almost everywhere ask you to keep records for several years, and how many depends on your country. Ask your accountant what applies to you. Put the old files in one folder, keep a backup copy somewhere else, and write down the last invoice number you used in each series. That note will save you a search later.

Once everything is moved, a weekly habit of matching bank payments to invoices keeps the new system true, which is the whole point of leaving the spreadsheet.

The short version

• Switch when numbering, tax, unpaid invoices or tax returns start taking real time.
• Start a new series at the start of your financial year, or use a new prefix mid-year so nothing repeats.
• Save your customer and item lists as CSV and import them.
• Chase old unpaid invoices from your old file. Do not issue them again in the new app.
• Keep your old files, backed up, for as long as your accountant says.