Most freelancers and small businesses don't lose money on invoices they forget to send. They lose it on the ones they send and then stop chasing. An invoicing app helps, but if you invoice a few clients a month from Word, Docs or a PDF template, a Google Sheet plus your Gmail is enough to see who owes you, what's overdue and who has gone quiet. This guide shows the columns, one formula, a simple reminder schedule, and how to use Gmail to check whether the client replied.
1. The columns
One row per invoice. Keep it boring:
| Column | What goes in it |
|---|---|
| A Client | The person or company name |
| B Email | The address you send the invoice to (accounts@… is common) |
| C Invoice no. | e.g. INV-1042 |
| D Amount | A number only; put the currency in its own column if you bill in more than one |
| E Sent | Date you sent it |
| F Due | Due date from your payment terms |
| G Paid on | Leave blank until the money arrives |
| H Next reminder | The date you plan to chase next |
| I Status | A formula (below) |
2. One formula for the status
In I2, then fill down:
=IF(A2="","",IF(G2<>"","Paid",IF(F2="","No due date",IF(F2<TODAY(),"OVERDUE "&(TODAY()-F2)&" days",IF(AND(H2<>"",H2<=TODAY()),"Chase today","Not due")))))Add a conditional formatting rule on the whole table (Format → Conditional formatting → Custom formula is) with =LEFT($I2,7)="OVERDUE" and a red fill, and another with =$I2="Chase today" in amber. Sort or filter by Status each Monday. A total of everything unpaid is =SUMIFS(D:D,G:G,""). It works the same in Excel.
3. A reminder schedule you can stick to
There is no legal rule for when to send reminders; what matters is that you send them consistently. A common pattern is:
- 3 days before the due date: a friendly heads-up with the invoice attached again.
- 7 days after: a firmer note that it's overdue, asking for a payment date.
- 14 days after: a final notice, then pick up the phone.
Put the next date from this list in Next reminder each time you send one. If you don't want to write each email from scratch, the free invoice reminder email generator writes the friendly, firm and final-notice versions from the invoice details, works out these three dates (optionally moving weekend dates to a weekday) and gives you a calendar file. It runs in your browser and doesn't send anything for you.
4. Reply on the original thread, then use Gmail to check
Send each reminder as a reply to the email that carried the invoice, so the client has the PDF right there and you have one thread per invoice. To check what happened, search Gmail:
INV-1042: every message that mentions the invoice number.from:accounts@client.com newer_than:14d: did they write to you in the last two weeks?to:accounts@client.com older_than:7d: your messages to them that are more than a week old.
If they replied with a question ("which PO number?"), the problem is now on your side: answer it before you send another reminder.
5. Late fees and interest: check your contract and local law
Some places give businesses a statutory right to interest on late business-to-business payments. Examples are the UK's Late Payment of Commercial Debts (Interest) Act 1998 (see the GOV.UK page in the sources) and the EU Late Payment Directive 2011/7/EU, which member states apply through their own laws. Rules differ by country and by type of customer (consumers are usually treated differently), so mention interest or fees only if your contract or local law allows it. This guide is general information, not legal advice.
6. When the sheet gets busy: let Gmail fill it in (optional)
Typing "last contacted" by hand works for five invoices. Past that, you start to miss replies. FollowSheet, our Google Sheets follow-up tracker, reads your Gmail to fill in when you last emailed each contact and who wrote last. It flags Needs reply when the client wrote last and Overdue when your Next follow-up date passes. It can't see your bank or invoicing app, so you still mark invoices paid yourself. The invoice reminder generator has a Copy as a FollowSheet row button that copies the client, amount, next reminder date and next step, ready to paste into the Contacts tab. The free plan covers 25 contacts; Pro is $7/month or $59/year, with a 14-day money-back guarantee. You don't need it for anything above.
Sources
- GOV.UK – Late commercial payments: charging interest and debt recovery
- EUR-Lex – Directive 2011/7/EU on combating late payment in commercial transactions
- Google Docs Editors Help – Use conditional formatting rules in Google Sheets
- Gmail Help – Search operators you can use with Gmail
Related guides
- Gmail follow-up tracker without a CRM
- Gmail follow-up reminders without an extension
- A free Gmail CRM in Google Sheets
Published 2026-10-06 by Karuna Labs. Our tools check file structure and checksums; always review outputs (and payment files in your bank's preview) before relying on them. This is general information, not financial, tax or legal advice.