How to Use ChatGPT or Claude as a Proposal Generator for Your Small Business

Writing a proposal takes time most small business owners don't have. You sit down, open a blank doc, and spend an hour getting the scope right, then another half hour on pricing, then you remember you need to add a case study — and suddenly it's been two hours for a job you might not even win. Most consultants, coaches, and tradespeople go through this every single week.

Here's the thing: ChatGPT and Claude can do the heavy lifting for you. Not with a generic template — with a draft that sounds like you, covers the right details, and is 80% ready to send in under ten minutes. This guide shows you exactly how to set it up.

What You'll Need

You need a ChatGPT account (the free tier gives access to GPT-5.3 with usage limits; Plus removes the limits) or a Claude account (also free with daily limits). Both work well for this. Claude tends to produce more natural, less "corporate AI" writing; ChatGPT is slightly better at structured tables and pricing breakdowns. Try both and see which output you prefer.

You also need one or two of your past proposals as reference material — something you were happy with that got accepted. You'll paste these into the chat to show the AI your style.

ChatGPT Option: Build a Custom GPT

If you use ChatGPT, the best approach isn't to paste instructions every time — it's to build a Custom GPT once, and it lives in your sidebar permanently. You open it, type the client brief, and it already knows everything about your business.

To create one: go to chatgpt.com/gpts/mine → Create → Configure. Give it a name ("My Proposal Writer"), then fill in the Instructions field with your setup (see the prompt template below). Under Knowledge, upload 1–2 of your past proposals as PDF or Word files — the GPT will reference them for tone and structure. Save it as private. That's it.

From then on, click your GPT, type the client brief, and get a draft. No setup, no pasting. Note: creating Custom GPTs requires ChatGPT Plus ($20 USD/month). Free users can use existing public GPTs but can't build their own.

Claude Option: Projects or a Reusable Prompt

Claude has Projects — available on the free plan with limits, and fully on Pro. A Project lets you save a set of instructions and upload files (like your past proposals) that persist across every conversation. It's the same idea as a Custom GPT: open the Project, type the client brief, done.

If you'd rather not set up a Project, the manual fallback works fine: write your instructions once, save them in a note or doc, and paste at the start of each new chat. Takes about 10 seconds.

The Prompt Template (use for either)

Whether you're configuring a Custom GPT or saving a Claude system prompt, use this as your starting point:

You are a proposal writer for [YOUR BUSINESS NAME], a [TYPE OF BUSINESS] based in [CITY], Australia.

Your job is to write professional client proposals in my voice — direct, friendly, and specific. No corporate jargon.

About my business:
- [2-3 sentences about what you do and who you work with]
- My typical packages are: [list your main offerings and pricing]
- My standard terms are: [payment terms, deposit, turnaround]

When I give you a client brief, write a proposal with:
1. A short opening that shows I understand their situation
2. What I'm recommending and why
3. A clear scope of work with deliverables
4. Pricing (use the packages above unless I specify otherwise)
5. Timeline
6. Next steps (e.g. "reply to this email to confirm, and I'll send an invoice for the deposit")

Keep it to one page if possible. Use my tone — here's an example of a proposal I was happy with:

[PASTE ONE OF YOUR PAST PROPOSALS HERE]

Fill in the brackets and paste a past proposal. For Custom GPTs, put this in the Instructions field and upload the proposal as a Knowledge file instead of pasting it inline.

Generate a Proposal in Minutes

When you have a new client to quote, open your Custom GPT or Claude Project (or a fresh chat with your system prompt pasted in), then give it the client brief. Keep it rough — just the key details:

New proposal needed:

Client: Sarah, runs a 12-person marketing agency in Melbourne
Project: Website redesign — they've outgrown their current site, want something that better represents their rebrand
Scope: New homepage, about, services, case studies pages. Migrating existing blog. No ecommerce.
Budget: They mentioned $8–12k
Timeline: Ideally live before end of financial year (June 30)
Extra context: They're a referral from a past client, so keep the tone warm.

Hit enter. In 30–60 seconds you'll have a full draft. It won't be perfect — maybe the pricing is slightly off, or there's a line that doesn't sound like you — but it'll be 80% there. A few edits and it's ready to send.

Tune It Until It Sounds Like You

The first few proposals will need more editing than later ones. Each time you edit, you can feed the correction back into the prompt: "The opening was too formal — in future, start by acknowledging the specific problem they mentioned." Over time your system prompt gets tighter and the drafts need less work.

Common refinements Australian business owners make:

• Add GST-inclusive pricing note ("All prices include GST")
• Specify you want AUD amounts, not USD
• Ask it to avoid phrases like "I hope this finds you well" or "Please don't hesitate to reach out"
• Include your standard late payment terms if relevant

What This Won't Do

AI won't replace the 10 minutes of thinking you need to do before writing any proposal — understanding the client's actual problem, whether the scope is realistic, and whether you actually want the job. It also won't know details you haven't told it: your current availability, whether you've worked with this client before, or anything specific to the project that wasn't in your brief.

The tool is best thought of as a fast first draft, not a finished product. You're still the one who reads it, edits it, and decides what to send.

How Much Does It Cost?

ChatGPT Free: $0/month — GPT-5.3 with usage limits, works fine for a handful of proposals per week
ChatGPT Plus: ~$35/month AUD (USD $20 + GST) — higher limits, required to create Custom GPTs
Claude Free: $0/month — daily limits, Projects included with some restrictions
Claude Pro: ~$30/month AUD — no daily limits, full Projects access

For most small business owners, the free tiers are enough to start. If you're writing more than 5–6 proposals a week, a paid plan removes the friction.