How do you calculate this „much more expensive“? I do not think this is correct estimate.

Just a few of the things you have to do when you have a bad hire that you fire (In the US and specifically California)

* Pay off any accrued time off

* COBRA insurance

* Unemployment

* Opening up the hiring pipeline (ads on job boards, recruiter, flights for potential candidates, training for new new employee)

* Potentially pulling other employees to fill the role while hiring again (Overtime and stress to existing employees)

Versus

Sending an email and saying no.

> Sending an email and saying no.

This is not that simple. Your hiring process is a funnel with certain conversion rates at wach step. If you overcomplicate it, your hiring timeline extends, increasing time to market for your projects and having some impact on the revenue. If you oversimplify it, risk of bad hire increases, but it may still worth it, if funnel gets much better.

Hiring someone isn't free, if only due to the opportunity cost of filling a role in your business with someone unsuitable.

I'd imagine the opportunity cost is offset by filtering out good devs with programming puzzles.

Consider that recruiters charge around 25% of 1 year of salary for helping to hire a developer, and the person-hour costs of hiring one person can easily exceed the recruiter cost for a small organization.

Firing also requires a fair amount of person-hours to do, and if you fire someone and need to replace them those costs stack.

Recruiting costs vary from one country to another. For me 25% is ridiculously high. Even considering cost of doing business, a recruiter would need to close just 5-6 open positions per year to earn as much as an engineer. If they work full time to achieve that, this is extremely inefficient for those money. Besides that, some recruiters actually offer warranty period that will cover thus specific case - you should not pay twice.

> How do you calculate this „much more expensive“?

By having actually done it, and understanding what processes are involved.

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> I do not think this is correct estimate

It is.