Self-Employment Alongside a Job: Consent, Advance Payments and Flat-Rate Tax

Find out when you need your employer’s consent, how much you will pay in advance payments, and whether you can choose the flat-rate tax alongside your job in 2026.

Are you allowed to run a business alongside your job?

Yes — being an employee does not in itself prevent you from running a business. You notify your trade using exactly the same procedure as anyone else, with no special restrictions for employees.

You only need your employer’s prior written consent if your new gainful activity is identical to your employer’s field of business — that is, effectively competing with it (§ 304 of the Labour Code). If you operate in a different field, you do not need consent under the law at all.

Consent is also not required for scientific, teaching, journalistic, literary and artistic activity (§ 304(2) of the Labour Code).
An employer may withdraw consent once given, but must give written reasons for the withdrawal; the employee must then end the gainful activity without undue delay.
You can check your employer’s field of business in the public Trade Register (rzp.gov.cz).

Why being a secondary activity pays off

Running a business alongside employment carries a key advantage for insurance purposes — it counts as secondary self-employed activity. You do not pay social (pension) insurance from it at all until your annual profit exceeds the decisive amount of 117,521 Kč (2026). What’s more, in the first calendar year of business advance payments generally are not due even above this limit — any shortfall only follows from your actual profit after the statement (přehled).

Health insurance for a secondary activity has no statutory minimum. So you do not pay advance payments up front — the premium (13.5% of 50% of profit) is settled in one lump sum according to your actual profit after filing the statement. This is a key difference from a main activity, where you pay a minimum advance payment of 3,306 Kč a month regardless of profit.

Income tax, however, is always declared, whether it is a main or secondary activity, and regardless of how much you earn. The only exception is occasional income outside a trade licence of up to 50,000 Kč a year (§ 10 of the Income Tax Act) — it is worth looking at that on its own if you are still deciding whether you need a trade licence at all.

Calculate your advance payments for a secondary activity

Select secondary activity and enter your expected annual profit. The calculator works out how much you will pay in social and health insurance for 2026 — and shows whether you are still below the decisive amount of 117,521 Kč.

Typ činnosti

Očekávaný roční zisk (Kč, nepovinné)

Orientační výpočet podle sazeb roku 2026. Nenahrazuje výpočet daňového poradce. Ověřeno 2026.

Beware of the decisive amount: 117,521 Kč

You only pay social insurance on a secondary activity once your annual profit exceeds 117,521 Kč (2026). Until then you pay nothing; once you exceed it, you pay at least 1,574 Kč a month. You will find a detailed breakdown for your situation in the guide Main vs. secondary activity →.

Frequently asked questions about self-employment alongside a job

Do I have to report my business to my employer?

You do not have to notify them by law, as long as your business is not identical to your employer’s field of activity. In that case, however, you need their prior written consent under § 304 of the Labour Code. For a different field, you need neither consent nor notification — but we still recommend telling them.

How much will I pay in insurance on a secondary income of 100,000 Kč a year?

You pay no social insurance at all — it is below the decisive amount of 117,521 Kč. Health insurance has no minimum for a secondary activity; you settle it according to your actual profit (13.5% of 50% of profit) only after filing the statement. Work out the exact amount for your field and expenses in the advance payments calculator.

Can I choose the flat-rate tax for a secondary activity?

No, not if you have a standard job where your wages are taxed by your employer’s monthly payroll withholding — the flat-rate tax rules out concurrent employment income (the only exception being a DPP or DPČ taxed by final withholding tax). Choose a lump-sum expense allowance or actual expenses instead, and file a standard tax return.

What if I also have a DPP with another employer?

You assess a DPP for the § 304 consent requirement in the same way as your main job — you only need consent if the field of business is identical. For tax purposes a DPP is separate income: if it is taxed by final withholding tax, it does not rule out the flat-rate tax; if it is taxed by monthly payroll withholding, the same restriction applies as for employment.

Is a non-compete clause different from consent under § 304?

Yes. Consent under § 304 covers running a business while the employment lasts. A non-compete clause (§ 310–311 of the Labour Code) is a contractual arrangement that restricts gainful activity only after the employment ends, in exchange for financial compensation of at least 50% of average earnings for a maximum of one year.

When does a secondary activity become a main activity?

As soon as the employment or other reason for the secondary activity ends — for example, finishing your studies or parental leave. From that month you pay the minimum advance payments as a main-activity OSVČ — social insurance 5,005 Kč (from 7/2026) and health insurance 3,306 Kč. More detail in the article Main vs. secondary activity →.

What to sort out next when you run a business alongside your job

Your First Order

How to issue your first invoice, what not to forget, and what details it must include.

Main vs. secondary activity

A detailed breakdown of advance payments, the 117,521 Kč decisive amount, and what to sort out in the first year.

OSVČ deadlines

An overview of deadlines for the tax return, statements and advance payments that you must not miss.

Side Income or a Trade Licence?

When occasional income of up to 50,000 Kč is enough, and when it pays to register an IČO.

U vedlejší činnosti se sociální pojištění platí jen při ročním zisku nad rozhodnou částku ' + kc(C.rozhodnaVedlejsi) + '; do té doby zálohy platit nemusíte. Zdravotní nemá minimum a doplácí se podle zisku.

Minimální sociální záloha hlavní činnosti se v roce 2026 snížila ze 40 % na 35 % vyměřovacího základu — od července 2026 činí minimum 5 005 Kč (do června 5 720 Kč), přeplatek se vrací.

Pozor na identifikovanou osobu: i bez překročení obratu se jí stanete, když přijmete službu od firmy z EU nebo ji do EU poskytnete (např. reklama na Google či Meta), nebo pořídíte zboží z EU nad ' + kc(C.dphIdentZbozi) + ' za rok. Identifikovaná osoba odvádí DPH jen z těchto přeshraničních plnění — tuzemský prodej zůstává bez DPH.