> there is never† a tax-related reason to refuse to take a higher-paying job This is usually true but not always. Where I live, if you as a self-employed cont

> there is never† a tax-related reason to refuse to take a higher-paying job This is usually true but not always. Where I live, if you as a self-employed contractor make revenue over the VAT threshold you must start charging VAT. If the clients are VAT registered business, they won't mind, they can reclaim it. But if they are not VAT registered, or if they are regular people not businesses, your price will effectively increase by 20% for them. To avoid losing business with the people who cannot reclaim the VAT, you may decide to lower the prices you charge to compensate. That's a cliff. You can be better off turning down a higher-paying job (such as a 3 month contract) that would put you over the VAT threshold, if you are close to it and would have to lower prices to everyone else to compensate, depending on your line of business.