Size a milestone invoice, retainage and what is not yet billable

About this exercise

You're billing a fixed-fee contract on milestones. Write a prompt for plain text with lines starting "Invoice now:", "Retainage:", "Cash expected:" and "Not yet billable:", each with the math. Only completed and accepted milestones are billable. Retainage is the percentage the customer holds back on each invoice. Under 70 words. No bullets or numbering.

Common mistakes when you ask AI for this

• Billing half of M2. The AI invoices M1 plus 50% of M2. Try: Add: "Only completed and accepted milestones are billable; ignore partial-completion billing."
• Forgetting retainage. The AI expects $18,000 cash. Try: Say: "Cash expected = invoice minus 10% retainage."
• Wrong not-yet-billable total. The AI leaves out M3 or counts M1 again. Try: Add: "Not yet billable: M2 and M3 amounts added."
• Markdown extras. The AI adds bold labels, headings and a closing note. Try: Say: "Plain text, no bold. Output only the lines asked for."
• Trusting the AI to count words. AI is bad at counting and runs past word limits. Try: Ask for fewer words than the real cap and keep each line short.

What a strong prompt includes

• Names the four lines
• Limits to accepted milestones
• Gives the retainage rule
• Ignores partial billing
• Caps length

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