Taxes for self employed people are much more complicated than taxes for salaried employees. Everywhere that I know, taxes from salaries are automatically withheld by the employer - those taxes have probably been calculated by a tax accountant in the first place. There's practically no way you'd need to pay extra taxes if your only income is your salary, so you can opt out of filing taxes.

For self-employed people there are many more rules and regulations: How to write off which kind of cost and purchase, filing VAT if required, etc. so that's already cost efficient if you hire someone qualified.