Memstack Business Invoice Generator

Invoice Generator — Creating professional invoice...

Generates professional invoices with line items, tax calculations, payment terms, due dates, and payment instructions — output as structured markdown ready for PDF conversion.

Activation

When this skill activates, output:

Invoice Generator — Creating professional invoice...

Then execute the protocol below.

Context Guard

| Context | Status | |---------|--------| | User says "invoice", "generate invoice", "create invoice", "bill client" | ACTIVE | | User says "line items" or "payment terms" | ACTIVE | | User needs a professional invoice for a client | ACTIVE | | User wants a contract or service agreement | DORMANT — use Contract Template | | User wants financial projections | DORMANT — use Financial Model |

Common Mistakes

| Mistake | Why It's Wrong | |---------|---------------| | "No invoice number" | Sequential invoice numbers are required for accounting and tax compliance. | | "Vague line items" | "Consulting — $5,000" invites disputes. Itemize by deliverable, hours, or phase. | | "No payment terms" | Without explicit terms (Net 30, due on receipt), clients have no obligation to pay on time. | | "Skip tax line" | Even if tax is $0, show the tax line. It demonstrates professionalism and compliance. | | "No late payment terms" | Without stated consequences, you have no leverage on overdue invoices. |

Protocol

Step 1: Gather Invoice Details

If the user hasn't provided details, ask:

> 1. Client — company name, contact person, billing address > 2. Your business — business name, address, tax ID / EIN (if applicable) > 3. Line items — what are you billing for? (description, quantity, rate) > 4. Payment terms — Net 30, Net 15, due on receipt? > 5. Tax — applicable tax rate? (state sales tax, VAT, or exempt) > 6. Currency — USD, EUR, GBP, etc.?

Step 2: Generate Invoice Number

Invoice numbering convention:

[PREFIX]-[YEAR][MONTH]-[SEQUENCE]
Example: INV-202603-001

| Component | Rule | |-----------|------| | Prefix | INV (standard), PRO (proforma), CR (credit note) | | Date | YYYYMM of invoice date | | Sequence | 001, 002, 003... (reset yearly or continuous) |

Alternative formats:

• Client-based: INV-ACME-001
• Project-based: INV-PROJ042-001

Step 3: Build Line Items

Line item table:

| # | Description | Qty | Unit | Rate | Amount | |---|------------|-----|------|------|--------| | 1 | [Detailed description of work/deliverable] | [X] | [hours/units/flat] | $[X.XX] | $[X.XX] | | 2 | [Detailed description] | [X] | [unit] | $[X.XX] | $[X.XX] | | 3 | [Detailed description] | [X] | [unit] | $[X.XX] | $[X.XX] |

Line item rules:

• Each line should describe a specific deliverable or time period
• Include enough detail to prevent client questions ("Website development" → "Homepage redesign — responsive layout, 3 revision rounds")
• For hourly work: include date range and total hours
• For project work: reference the SOW or contract phase
• For expenses: mark as "Reimbursable expense" with receipt reference

Totals calculation:

Subtotal:                    $[sum of line amounts]
Discount ([X]%):            -$[discount amount]
Subtotal after discount:     $[adjusted subtotal]
Tax ([X]% [tax name]):      +$[tax amount]
──────────────────────────────────
Total Due:                   $[final total]

Step 4: Set Payment Terms

Standard payment terms:

| Term | Meaning | Best For | |------|---------|---------| | Due on receipt | Pay immediately | Small amounts, first-time clients | | Net 15 | Due within 15 days | Freelance, small projects | | Net 30 | Due within 30 days | Standard business term | | Net 60 | Due within 60 days | Enterprise, government | | 50/50 | 50% upfront, 50% on completion | Projects >$5,000 | | Milestone | Payment at each project phase | Large projects |

Late payment clause:

Late Payment: Invoices not paid within [X] days of the due date will
incur a late fee of [1.5]% per month ([18]% annually) on the outstanding
balance. All collection costs, including attorney fees, will be the
responsibility of the client.

Early payment discount (optional):

2/10 Net 30: 2% discount if paid within 10 days; full amount due in 30 days.

Step 5: Add Payment Instructions

## Payment Methods

**Bank Transfer (preferred):**
Bank: [Bank name]
Account name: [Business name]
Routing number: [XXXXXXXXX]
Account number: [XXXXXXXXX]
Reference: [Invoice number]

**Online Payment:**
Pay online: [Payment link — Stripe, PayPal, or Square invoice URL]

**Check:**
Make payable to: [Business name]
Mail to: [Mailing address]
Memo: [Invoice number]

**Wire Transfer (international):**
SWIFT/BIC: [Code]
IBAN: [Number]
Bank address: [Address]

Step 6: Assemble the Invoice

Invoice template:

─────────────────────────────────────────────────────────

                        INVOICE

─────────────────────────────────────────────────────────

**From:**                          **Invoice #:** [INV-YYYYMM-NNN]
[Your Business Name]               **Date:** [Invoice date]
[Your Address]                      **Due Date:** [Due date]
[City, State ZIP]                   **Terms:** [Net 30 / etc.]
[Email]
[Phone]
[Tax ID: XX-XXXXXXX]

**Bill To:**
[Client Company Name]
[Client Contact Name]
[Client Address]
[City, State ZIP]
[Client Email]

─────────────────────────────────────────────────────────

| #  | Description                     | Qty  | Rate      | Amount    |
|----|---------------------------------|------|-----------|-----------|
| 1  | [Line item description]         | [X]  | $[X.XX]   | $[X.XX]   |
| 2  | [Line item description]         | [X]  | $[X.XX]   | $[X.XX]   |
| 3  | [Line item description]         | [X]  | $[X.XX]   | $[X.XX]   |

─────────────────────────────────────────────────────────
                              Subtotal:      $[X,XXX.XX]
                              Tax ([X]%):    $[XXX.XX]
                              ──────────────────────────
                              **TOTAL DUE:   $[X,XXX.XX]**
─────────────────────────────────────────────────────────

## Payment Instructions
[From Step 5]

## Terms
- Payment is due within [X] days of invoice date.
- [Late payment clause from Step 4]
- [Early payment discount if applicable]

─────────────────────────────────────────────────────────
Thank you for your business.
─────────────────────────────────────────────────────────

Step 7: Recurring Invoice Setup

For ongoing retainer or subscription billing:

## Recurring Invoice Schedule

| Invoice # | Period | Amount | Due Date | Status |
|-----------|--------|--------|----------|--------|
| INV-202601-001 | Jan 2026 | $[X] | [Date] | Paid |
| INV-202602-001 | Feb 2026 | $[X] | [Date] | Paid |
| INV-202603-001 | Mar 2026 | $[X] | [Date] | Current |
| INV-202604-001 | Apr 2026 | $[X] | [Date] | Upcoming |

Automation tips:

• Use Stripe Invoicing, QuickBooks, or FreshBooks for recurring invoices
• Set automatic payment reminders: 3 days before due, on due date, 7 days overdue
• Auto-generate the next invoice on a fixed schedule (1st of month, etc.)

Output Format

Deliver the complete invoice in the template format from Step 6, ready to be:

• Converted to PDF (via Pandoc, browser print, or invoicing tool)
• Pasted into an invoicing platform
• Sent directly to the client

Completion

Invoice Generator — Complete!

Invoice #: [Number]
Client: [Name]
Line items: [Count]
Subtotal: $[Amount]
Tax: $[Amount]
Total due: $[Amount]
Payment terms: [Terms]
Due date: [Date]

Next steps:
1. Review all line items for accuracy
2. Convert to PDF or enter into your invoicing tool
3. Send to client with payment instructions
4. Set a calendar reminder for the due date
5. Follow up if not paid within 3 days of due date

Level History

• Lv.1 — Base: Invoice numbering convention, detailed line items with totals/tax/discount, 6 payment term options, late payment clause, early payment discount, 4 payment method templates (bank, online, check, wire), complete invoice template, recurring invoice schedule, automation tips. (Origin: MemStack Pro v3.2, Mar 2026)

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: cwinvestments
• Source: cwinvestments/memstack
• License: MIT
• Homepage: https://memstack.pro

Install and usage instructions live in the source repository linked above.