How to Track Invoices and Retainers in Google Sheets

A good invoice tracker answers three questions in seconds: who has paid, who still owes you, and how much of each retainer is used. You need five columns and three formulas.

The columns to use

Give every invoice one row. Keep the columns in this order so the formulas below work as written.

Use a dropdown for Status (Data > Data validation) with three options: Sent, Paid, Overdue. A fixed list keeps your totals accurate because nobody types "pd" or "paid!".

Formulas that do the chasing for you

Days overdue, in column F:

=IF(AND(E2<>"Paid", TODAY()>C2), TODAY()-C2, 0)

Total still owed to you:

=SUMIFS(D:D, E:E, "<>Paid")

Total overdue:

=SUMIFS(D:D, E:E, "Overdue")

Add conditional formatting to column F (Format > Conditional formatting, greater than 0) so overdue rows turn amber.

Tracking retainers

On a second tab, give each retainer client a row with the hours or deliverables included and the amount used so far. Percent used is =Used/Included. When a client passes 80%, it is time to mention the renewal or an overage.

Keep it weekly

Update the tracker when you send an invoice and when money lands. A five-minute check every Friday is enough to catch late payers before they become a problem.