Invoice and AR — generate, send, and chase

TL;DR. Take a list of billable items and produce client-ready invoices, then track which are paid and chase the rest — without copy-pasting into a templating tool every Friday afternoon. Three hours a week of AR-clerk time saved at steady state.

Job to be done#

Take a list of billable items (project hours, subscription renewals, milestone payments) and produce client-ready invoices, then track payment status and chase what is overdue.

Who runs it#

AR clerk or part-time controller in a 50–500 person services or SaaS business.

Inputs (inbox/)#

• Time-tracking export — CSV from Harvest, Toggl, or your internal tool
• Subscription renewal list — CSV from your billing system or CRM
• Client master file — Excel with name, address, tax ID, payment terms, currency
• Optional: a previous invoice template as a branding reference

Outputs (output/)#

• One PDF invoice per client, named YYYY-MM-DD_[client]_INV-[number].pdf
• A Word source per invoice so finance can edit before sending
• An updated AR ledger (Excel) with status: Sent / Paid / Overdue
• A reminder schedule (Excel) for chase cadence

Prompt seed#

Read /inbox/time-tracking-[month].csv and /inbox/clients.xlsx.
For each client with billable hours this month, generate one invoice
as a Word doc and a PDF in /output/invoices.
Use the template style from /inbox/template-invoice.docx.
Filename format: YYYY-MM-DD_[client]_INV-[next-number].pdf.
Append a row per invoice to /output/ar-ledger.xlsx with status "Sent".
Plan the run before generating; flag any client missing a tax ID.

Quality bar#

• Currency, tax ID, and payment terms always pulled from the client master, never inferred.
• Invoice numbers are sequential and gap-free.
• Total math is verified line-by-line, never blindly summed by Cowork.
• "Net 30" and similar terms are calculated, not pasted ("Due 25 May 2026", not "Net 30").
• Common trip-up: half-day billable rules, retainer offsets, and pro-rated subscription renewals. Encode the rules in CLAUDE.md.

Time saved (typical)#

Around 3 hours per week of AR-clerk time at steady state. Often 6+ hours in the first month while rules get tuned.

Upgrade path#

• After 30 days of stable runs, convert to a monthly-invoicing skill.
• Add a connector to your billing system — Stripe, Chargebee, Recurly. See MCP connectors.
• Schedule the run monthly at the close cadence.

Tinkso's take#

The first three months expose every edge case: half-day billing, retainer reductions, FX conversions, weird client requests. We coach AR clerks to keep an "edge case" tab in CLAUDE.md and update it as exceptions appear. By month four the prompt handles 95% of clients straight through, and the edge-case tab becomes the change log.

Try this#

Run the seed prompt on last month's data in a test workspace. Compare the result to the invoices that actually went out. The diffs are your prompt's homework — and the most efficient way to surface every business rule that lives in someone's head.