It's completely normal. Just say "I can offer you X" Nothing more to it. Everyone always starts "far higher, far lower" on each end. Don't make a big fuss, at all, about the 50% aspect. Don't even mention the 50% aspect. Just state "we can offer you X". It's a non-issue, 50% is nothing in a negotiation. (If the person ends up going somewhere else, good luck to them, right?) Bottom line: it's commonplace to have such differences in a salary negotiation.

You may want to make sure you both mean the same thing by "salary". It sounds like you take it to mean "wages" and he may mean "total compensation package, including benefits." Get on the same page first - then decide whether or not it's worth pursuing.

Also be sure to mention, that if you offer X and X is your max offer then state so, otherwise it might be interpreted there's leeway for more negotiation between your proposal and his expectation.

Of course it would depend on many factors - your budget, the requested salary in relation to others on your team, your company's salary brackets (if any), etc. For me, an ask of 50% greater than offered tells me that someone's expectations are too far out of whack to be negotiable - I cant tell which side is off. If it were me, I'd move on.

You are assuming that this person knows how to start salary discussions. Perhaps their friend told them to start at 50% above the market rate. You don't know until you ask. Just tell them bluntly and politely, "Our market research shows this position is worth about "X" and we're willing to offer that." If they balk, then say, "We'd love to you have you, but I think what you want may be way out of reason, but, if you reconsider, give me a call." That way, you leave the door open if they really don't know what they're doing.

Only 50% mismatch? In a typical Middle Eastern souk, it's quite normal for a seller to start by demanding $1,000 and a buyer to offer $10, and for both to be happy with the bargain when they meet in somewhere in the middle! Don't start "negotiating" by making your best possible offer. Give your self wiggle room to improve it a bit, maybe in less tangible ways that just salary (e.g. flexible working arrangements, etc).

Did the job description detail the position accurately? If the candidate is serious, it could mean that you are looking for an intermediate developer of 5 years experience, while the candidate is a senior developer with 12 years experience.

Thanks for all the input everyone: this is all very helpful. @JuhaUntinen, in this case the candidate pretty much came out of the blue. We advertised a position for a full stack engineer and he emailed us directly with his resume as a front-end HTML/CSS person. He understood the fact that he was not the candidate we were asking for in our job posting, but we have a variety of needs (including an expert in those skills), so we interviewed him anyway. As a result, there was no stated salary expectations (although his asking salary is at the high end of the posted engineer salary range).

While @alephzero's comment is amusing and interesting, I think it's less applicable in some job markets. Especially when it comes to tech talent, there are often multiple simultaneous offers out for top talent, and so it's better to offer close to (not at) your best offer out of the gate, so that you can negotiate or convince them. That said, I agree with the answer below that says it's worth another conversation, even if you don't do the work of the formal offer. Educate yourself in their thought process and see if your market research for the area is off or if the guy is just an egotist

@conor Exactly how relevant the candidates experience is, and what you (and they!) expect the role to be is an important area for the negotiation. (For example) If you have a job for an intermediate data scientist, and end up choosing a PhD level expert data wizard, their role will expand, and they're reasonable in asking for an expert level salary even though it'll be way beyond the initial budget. If their additional experience won't be relevant to the role, then they need to accept the salary hit.

@mbrig I think that is part of the problem. It sounds like at his current job he has a wide variety of different responsibilities. However, he billed himself to us as a front end HTML/CSS person, which is the skill set I was interested in. His other skills aren't of real value to us, and other skills that would make him more valuable to us are things that he doesn't have. As a result, his value to us is largely driven by his value as an HTML/CSS person (i.e. not as much as an engineer), but he might legitimately be worth more to other companies.

One difference between a person and a rug is that the rug deal is done once the money and rug change hands. The person has to make a daily decision to keep accepting the salary s/he is being paid. Therefore it is more important that both sides find the deal acceptable.

Not a complete answer, but a viewpoint from someone that's been in your candidate's situation: If you absolutely cannot afford to pay him closer to his asking salary, just move onto the next candidate. Don't try to negotiate, it's a waste of both sides' time. He probably has (or will have) other offers at the pay he's looking for, so it's a dead end. In the future, establish salary expectations early on - it'll save you both time and effort.

"HTML/CSS person" sounds very strange to me. Honest question: Wouldn't another expression like "HTML/CSS developer" be preferred?

The candidate could just be hedging their bets, or completely uninformed.

This is why to save your self and the candidate time you advertise a salary band you're willing to pay. If you don't, candidates will expect a negotiation and will high ball their expectations expecting the employer to low ball. It's very simple and straight forward. If you're not willing to negotiate, from a candidates perspective it doesn't say much about any potential career progression does it? The first thought I'd have (and have had in the past) is that the employer isn't willing to negotiate now, they never will be even as seniority increases.

@OldBunny2800, I've never seen that before. His role wasn't really covered, although maybe that is the source of confusion. The closest role (from the stack overflow calculator) would be a web developer. However, he doesn't actually have much programming experience (he primarily does HTML and CSS), so I wouldn't consider him a web developer. Maybe that is part of my confusion? Would an HTML/CSS developer with 10 years experience get paid as much as a PHP engineer with 10 years experience, for example?

All of these answers (and subsequent discussion) have been very helpful. Starting some more interviews this next week, and this has all been great input. I'm not sure if any of them is really the "right" answer, so I'll just accept the one with the highest score thus far.

@ConorMancone Asking an employee for Salary expectations and expecting them to lowball themselves is ridiculous because they're practically guaranteed to not receive an offer higher than they're asking. For that reason, many job seekers will give a higher number than they're willing to work for, with the expectation that the company will give a counter offer.