Right, letters. Complaints, requests, thank-yous, and the ones nobody wants to write, like condolences. AI is genuinely good at the first draft of all of these. Not the finished thing, mind you, but the bit where you’re staring at a blank page not knowing how to start. That’s the bit it solves.

What you’ll be able to do

By the end of this you’ll know how to get ChatGPT, Claude, Gemini or Copilot to draft a letter that actually sounds like it’s going somewhere, not just generic filler. A complaint about a faulty washing machine. A request for a rent extension. A thank-you to someone who did you a favour. Even the awkward condolence letter you’ve been putting off. Same basic method for all of them: give the AI the facts, tell it what you want to happen, and ask for the right tone.

Before you start

AI doesn’t know your situation. It knows patterns of how letters are usually written, and it’ll use those patterns to fill in gaps you didn’t mean to leave. So if you don’t tell it the date your washing machine broke, it might just make one up, or leave a vague placeholder like “[insert date]” and hope you notice.

Before you open any AI tool, gather the actual details. For a complaint: dates, amounts, order or reference numbers, what you were told and by whom. For a request: what you’re asking for, why, and by when. For a thank-you or condolence: the person’s name, what happened, and how you know them. This sounds obvious, I know, but it’s the single biggest difference between a draft you can send and one you have to rewrite from scratch.

It also helps to know roughly how firm you want to sound. Not shouty, but the AI needs a steer, firm-but-polite, warm-but-brief, that kind of thing. Vague instructions get you a vague letter.

Get set up

You don’t need anything fancy. ChatGPT, Claude, Gemini and Copilot all handle letter-writing fine, and most have a free tier that’s enough for this. Pick whichever one you already have an account with, that’s honestly the best starting point. If you’re on a Mac or iPhone, Apple Intelligence Writing Tools can rewrite text you’ve already drafted, right there in the app, which is handy for a quick pass. If you use Word, Copilot does something similar inside the document.

Once you’re logged in, the basic shape of a prompt is this: say what the letter is for, give the key facts, and say what tone you want. Something like “write a complaint letter about a faulty product” will get you a letter, but it’ll be generic. Add the details and it gets useful fast.

If you want the letter to actually sound like you, rather than like every other AI-generated letter out there, that’s a slightly different job, more about your own voice and patterns than about facts and tone. ScriptGrain, one of ours, is built for that specifically. Worth knowing it exists, though for most letters here you don’t need it.

Try it yourself

Here are three prompts. Copy them, swap in your own details, and adjust the tone line if it doesn’t fit.

A complaint letter, the kind where you know your rights but don’t want to sound aggressive:

Write a formal complaint letter to a retailer about a faulty item.

Facts:
- Item: washing machine, bought 14 March, order number 8827364
- Fault: stopped working after 6 weeks, engineer visited and confirmed a manufacturing defect
- I've already called customer service twice with no resolution
- Under the Consumer Rights Act 2015 I'm entitled to a repair, replacement or refund

What I want: a full refund within 14 days

Tone: firm but polite, no threats, just clear about what I expect and by when

A request letter, say for something from your landlord or a service provider:

Write a letter requesting a one-month extension on my tenancy break clause.

Facts:
- Current tenancy ends 30 June
- I need until 31 July due to a delayed house purchase
- I've been a reliable tenant for 3 years with no missed payments
- Landlord's name: Mr Patel

What I want: agreement to extend by one month, in writing

Tone: polite and appreciative, not demanding

A thank-you or condolence letter, the ones that are hardest to start:

Write a short thank-you letter to a colleague who covered my work for two weeks
while I was in hospital.

Facts:
- Her name is Sarah
- She took on my projects with no notice and kept clients happy
- I want to mention I'm back and grateful, without making it too long

Tone: warm, genuine, not overly formal

Notice the pattern. Facts first, outcome second, tone last. That order matters, it’s basically giving the AI a brief rather than a vague wish.

Check the result

Don’t just read the letter and think “yeah, that’ll do.” Actually test it.

First, check every fact against what you gave it. Dates, amounts, names, reference numbers. AI can occasionally shift a number or misplace a date, especially if your original prompt was a bit rushed. Read it slowly, out loud if you can, and compare against your notes.

Second, check the tone actually matches what you asked for. Sometimes “firm but polite” comes out sounding either too soft or a bit stiff and legal-sounding, like it’s trying to impersonate a solicitor. If that’s happened, that’s fine, it’s fixable, just ask for a rewrite.

Third, read it as if you’re the person receiving it. Would this land well? Does the complaint letter sound like someone who knows their rights, or like someone who’s had ChatGPT write an angry letter for them? There’s a difference, and it usually comes down to specific detail versus generic phrasing.

Fourth, check length. AI has a habit of padding things out, extra sentences that don’t add anything. A good complaint letter is often shorter than the first draft you get.

None of this takes long. Five minutes, maybe.

If it doesn’t work

Sometimes the draft just isn’t right. Usually it’s because the prompt was too thin, so go back and add more detail: exact dates, what was actually said to you, what outcome you specifically want. The AI can’t read your mind, only your prompt.

If the tone’s wrong, tell it plainly. “Make this less aggressive” or “this sounds too formal, make it warmer” works better than starting over. You can also ask it to shorten a letter, or to remove any part that sounds like a threat, which complaint letters sometimes drift into without you asking for it.

Now, the important bit. Never paste account numbers, passwords, National Insurance numbers, or anyone else’s personal details into an AI chat. Reference numbers for an order are usually fine, they’re not sensitive on their own, but bank details, full addresses of third parties, or anything that identifies someone who isn’t you, leave it out. Use placeholders instead, like “[account number]”, and fill those in yourself once you’ve copied the letter out. Most AI tools state in their own privacy documentation that conversations may be used to improve the service unless you’ve turned that off, so treat the chat window like a public noticeboard, not a locked drawer.

If you’re writing on behalf of someone else, like a condolence letter for a shared loss, be careful about how much detail you share about the deceased or their family. Keep it general, or write that part yourself once you’ve got the AI’s structure to work from.

Keep exploring

If the letter’s basically right but the phrasing feels clunky, have a look at “How to get AI to edit my writing”, that’s a tighter, more focused pass than a full rewrite. If you end up sending a lot of these by email rather than post, “How to get AI to send emails for me” covers the bits specific to that. And if every AI letter you get sounds a bit too polished, a bit too much like everyone else’s, “How to get AI to sound like me” is worth a read, it’s about keeping your own voice in there.

Sources and review notes

Review date: 15 September 2026 — every source above was opened and checked against the text on that date.

Disclosure: ScriptGrain is one of our products — this site is made by the same studio, Adapt Progress Evolve. We have tried to compare fairly, and the alternatives named are real and worth a look.