Monthly Invoicing Checklist
A monthly invoicing checklist for agencies and service firms: collect billable time and fixed fees, check invoices, send them on time and follow up on payments.
- Typical schedule monthly
- The checklist 4 sections, 17 items
- Variables
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Use this checklist for the monthly billing run: the day you turn last month's work, retainers and recurring fees into invoices. It fits agencies, consultancies, IT service firms and any business that bills clients for time, projects or contracts rather than through an online checkout.
Who owns it
Finance or the office manager owns the run and sends the invoices. Project leads or account managers confirm what is billable for their clients before the invoices go out. Agree a fixed date for that confirmation, such as the second working day of the month. Otherwise invoicing waits on the slowest reply.
Common pitfalls
- Unlogged time. Time that is not logged by the cut-off is often never billed. Remind the team before the month ends, and check for people with unusually low hours.
- Invoices that do not match the contract. Wrong rates, a forgotten discount or the wrong purchase order number lead to rejected invoices and late payment.
- Missing the client's process. Larger clients often require a PO number, a specific address or upload to a supplier portal. An invoice sent to the wrong place may never be paid.
- No follow-up. Sending invoices is half the job. Review overdue invoices every billing run.
A monthly scheduled run in Runbook keeps the steps and the client confirmations in one place. Adapt this to your jurisdiction, especially invoice content and VAT rules; it is a practical checklist, not tax advice.
The checklist: Invoicing run {{month}}
Collect billable work
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Remind the team to log all time for
{{month}}by the cut-off date -
Export billable time and expenses for
{{month}}from the time tracking tool (e.g. Harvest, Toggl, Clockify) -
List recurring fees, retainers and support contracts due for
{{month}} -
List project milestones reached in
{{month}}that trigger an invoice -
Project leads confirm billable amounts and write-offs for their clients
Prepare invoices
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Create draft invoices for each client in the invoicing system
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Check rates, discounts and caps against the contract or statement of work
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Add the client's PO number, reference or cost centre where required
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Check the tax treatment for each client, including reverse charge for foreign business clients
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Attach time reports or delivery notes where the client expects them optional
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Second person reviews invoices above an agreed amount, or for new clients
Send
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Send invoices to the correct billing contact, or upload them to the client's supplier portal
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Confirm invoices are numbered in sequence with no gaps or duplicates
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Post the invoices to the ledger, or confirm they synced from the invoicing tool
Follow up
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Review the aged receivables report and send reminders for overdue invoices
Use a friendly reminder first, then a phone call to the client contact for anything well past due.
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Escalate long-overdue invoices to the account owner and decide on next steps
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Record unbilled work or disputes to resolve before next month's run
Checklist as Markdown
Frequently asked questions
What should be on an invoice?
At a minimum, your business details, the client's details, a unique sequential invoice number, the date, a description of the goods or services, the amounts and the payment terms. If you are VAT registered, most countries also require your VAT number and the tax rate and amount. Check the local rules, as requirements differ.
When should I send monthly invoices?
As early as possible after the month ends, ideally within the first few working days. Payment terms only start when the client receives the invoice, so every day of delay pushes your cash in later. Fixing a cut-off date for time logging and project confirmations makes early invoicing realistic.
How do I reduce late payments?
Send correct invoices on time, to the right contact, with any PO number the client requires. Agree clear payment terms in the contract, send a reminder shortly after the due date and call before things get very late. Reviewing overdue invoices in every billing run keeps it from being forgotten.
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