How do I consult for a previous employer.

Just remember that "consult" is derived from "con" and "insult". "Con" means to trick somebody, so you need to insult them while tricking them into believing that you are supplying a worthwhile service.

If the exit wasn't great, will they be open to you working in a consultant role?

I'm assuming that your idea will increase efficiency, or reduce costs, or similar. My initial plan would be to go to them with a business case saying I can help you do x, with a breakdown of how that's achieved. The fun part will be doing that without giving the game away.

In the more medium turn once you work with them and tell them what your secret sauce is, what's to stop them cancelling the contract and going it alone? Maybe something whereby you take a percantage of the money saved for a period of time is the way to go.

Good luck

What were the terms of your previous departure? Make sure they’re not setting you up by saying your knowledge was acquired in your previous role and they’ll not pay you.

How do I approach them without giving them my ideas, to ask for some kind of consultancy role.

I suppose the trick is to try and understand in what sense your ideas can be 'owned' by you - whether they are genuinely unique - ie you've invented something, or an innovation (clever application of something that exists) or an efficiency.

As a consultant you don't have any job security so whats to stop them employing you for an hour, witnessing your genius and then applying your ideas in any way they like?

The sector you're working in can dictate how sensitive people are to valuing 'ideas'. In certain private sectors 'ideas' are recognised as commercially valuable and something to be protected and rewarded for. Its generally understood that very few people actually have many ideas - a lot of the ideas people think they have is actually just remembering something they saw elsewhere. In public and voluntary sectors 'ideas' are seen as something to be taken, used and shared for the wider benefit and there's no really grasp of the notion that they can belong to someone and that you might be taking and using something that isn't yours.

Offer to consult for free but take a cut of any benefit they derive from it? That way you can agree terms before spilling the beans, and there would be no up front costs for them which might make them more agreeable.

Start a new franchise on your own if the idea is that great.

I don't know how you could verify how much extra profit (and your percentage of that) would be without having full access to the accounts.

The ideas don’t really apply to the competition, so I can’t flog them elsewhere.

this is your first mistake, no true consultant would let the inappropriateness of an idea stop them applying it to a situation in which they'll also get paid to fix the mess afterwards.

Offer to consult for free but take a cut of any benefit they derive from it? That way you can agree terms before spilling the beans, and there would be no up front costs for them which might make them more agreeable.

Isn't there a story of someone who came to a toothpaste company with an idea to increase sales and wouldn't tell them what it was until they agreed to pay him? Once they agreed he simply said "make the hole bigger".

Heard it years ago, no idea if it's true or not.

Are your ideas patentable or copyrightable?

I'd establish and protect your IP Before approaching them.

Don't go with a request to consult, offer to sell them the rights to the idea either for a one time sum, or for a cut of any future profits derived (essentially royalties), and walk away again.

If they use your (protected) idea you have a right to a proportion of any profits, if they choose not to you've not had to engage and negotiate with a potentially bitter ex employer for a protracted period.

If it wasn't a "great exit," I'd derive more pleasure from knowing that I could make them better but I'm not going to.

Thanks all, the above issues have been flying around in my head TBH. The big idea is not something that is IP proof... Difficult, and Cougar you have it in one- I certainly don't want them to gain from it unless I get paid.

Isnt this something to approach a competitor with rather than going back to your previous business / employer?

“make the hole bigger”.

In the OP's line of work I hope this isn't one of  the new ideas. Could be a useful negotiation technique though - along the lines of Marathon Man.

Maccruiskeen, I wish it was! It is a really specific solution for a problem they don't know about, in one area of the business. Sounds unhelpful as I'm writing it.

I left a job under what I thought was a cloud. A whole bunch of rows about me being shit followed by an appraisal that basically said "you're shit". So I resigned on the basis that they didn't like me working for them and neither did I. So when they approached me to Freelance for them at inflated fees I couldn't understand it? Cue phone conversations about "you were an experienced, respected, professional member of the team...blah" when I pointed out the discrepancy between this and my appraisal they admitted that that's just how they work "to manage expectations" and who else could do what I'd been doing?
Makes you think.

Makes you think.

…that you can charge a significant rate, work at a favorable pace, and anticipate ‘contractual difficulties’?

It sounds like the idea is the valuable thing, not your consulting work to solve a yet unsolved problem or to implement your idea. If they could implement it themselves.

Regardless, I'd expect a company to be more likely to be competent in hiring a consultant than buying an idea, so it might well be the best bet to getting paid.

There are NDAs, maybe there are similar things for non-use. No idea how difficult they are or how willing companies would be to sign one in this situation.

How long ago were you employed by them?

Are you sure there aren't any clauses in your employment contract which would mean the company "owns" any IP which could be deemed to have been attained whilst being employed by them, and they, therefore, "own" that IP?

OK, this is actually quite tricky if you didn't leave on good terms, and might not be very possible.

You can't patent it.
You can say it's worth this much , but you don't know and you can't prove that.
It sounds like a tweak, or an efficiency saving?

You need to call them , and say you have an unspecified idea that will achieve this. This might be uncomfortable, but that's life, and if it's a good enough idea they won't worry so much. How much do you think it's worth? How much do you think they should pay you?

How long will it take to explain or setup? Your worst situation is that you go in, make the sales pitch, they say no , and then do it under their own steam anyway.

If they don't currently know that they have this problem, would it be possible to tell them about their problem without telling them your solution, and then say "I can help you fix this but it will cost you x"?