Additional money alongside a job can be earned legally in several ways: within unregistered business activity (działalność nierejestrowana), under a civil-law contract, through one's own business, from private rental or the sale of unneeded items. Each of these paths has different effects in PIT and ZUS, and the choice depends mainly on the scale of revenue and whether the client needs an invoice. In principle, the employer does not need to be informed of anything, unless the employee is bound by a non-compete agreement.
Five legal sources of additional income
| Form | For whom | Main constraint |
|---|---|---|
| Unregistered business activity | small services and sales, e.g. tutoring, handicraft | revenue up to PLN 10,813.50 per quarter (2026), no business in the last 60 months |
| Mandate or specific-task contract | one-off projects for one principal | settled by the principal, the contract must match the nature of the work |
| Sole proprietorship (JDG) | steady cooperation, corporate clients, abroad | CEIDG entry, accounting, health contribution |
| Private rental | flat and room owners | 8.5% ryczałt, and 12.5% above PLN 100,000 of revenue |
| Sale of private items | used equipment, clothes, collections | tax when the sale takes place before six months from the end of the month of purchase |
Unregistered activity — starting without formalities
This is a solution for those who want to test an idea on a small scale. In 2026 the quarterly revenue limit is PLN 10,813.50, i.e. 225% of the minimum wage (PLN 4,806). There is no need to register a business or pay ZUS contributions on this account, and the income is reported in the annual return. Only persons who have not run business activity for the last 60 months can take advantage of it.
Once the limit is exceeded in a quarter, the activity becomes a business and within 7 days an application must be filed with CEIDG. The details and effects for the length of service are described in the article on unregistered activity.
Mandate contract and specific-task contract with another entity
For an employee it is crucial with whom the additional contract is concluded. If the principal is the employee's own employer or the work is performed for them, the revenue from the contract is for ZUS purposes treated the same as salary from the employment relationship and is subject to full contributions.
When the principal is another company and the salary from employment is at least the minimum wage, the pension and disability insurance from the mandate are voluntary (Article 9(1) and (1a) of the Act on the Social Insurance System). The health contribution, however, is deducted from each mandate contract. A specific-task contract concluded with an outside entity does not trigger ZUS contributions, but it must concern a specific, verifiable result — describing ordinary, repetitive work as a "dzieło" is a common cause of audits.
Own business alongside a job
Running a sole proprietorship pays off when revenue is regular, clients expect invoices or the cooperation is to be long-term. It requires entry in CEIDG and bookkeeping, and the form of taxation — scale, flat tax or ryczałt — is chosen separately for the business. If the employment contract pays at least the minimum wage (PLN 4,806 gross in 2026), pension and disability contributions from the business are not mandatory, but the health contribution must be paid. The overlap of insurance titles, the double health contribution and tax settlement are discussed in detail in the article a job and own business, and the plan for a full transition to a business — in the article on switching from employment to JDG.
Rental and sale of private items
Revenue from renting a flat outside business activity is settled with ryczałt: 8.5% up to PLN 100,000 per year and 12.5% on the surplus. The same tax covers short-term rental, though the question of the border with business activity arises more often there.
Selling your own used items — e.g. a bike, console or phone — is not taxed if six months have passed from the end of the month of purchase (Article 10(1)(8)(d) of the PIT Act). An earlier sale at a profit requires reporting the income. Buying goods for resale is already trade, which falls within unregistered activity or business.
Does the employer have to know about the extra earnings
The Labour Code does not impose on the employee a general obligation to report additional work. The restriction follows only from a separate non-compete agreement (Article 101¹ § 1 of the Labour Code), which is valid only in writing. Within its scope, the employee may not conduct competing activity or work for a competitor, and the employer may claim damages.
Regardless of such an agreement, an additional occupation may not conflict with duties: working for your own clients during working hours, using company equipment or using the employer's confidential information may end in disciplinary termination. Separate rules restrict additional activities, among others, in the civil service and some public professions.
How to choose the form — a short decision path
- Estimate quarterly revenue. If it fits within the limit and the client does not need a VAT invoice, start with unregistered activity.
- For a one-off project for a company, consider a mandate or specific-task contract — settlement is taken over by the principal.
- For regular assignments or revenue above the limit, set up a business and compare the forms of taxation.
- Before starting cooperation, read your employment contract and any non-compete agreement.
- Keep the documents: contracts, bills, transfer confirmations and purchase proofs for items sold.
How Good Balance can help
We help choose the form of additional activity and take you through sole proprietorship registration, and then run simplified accounting, taking into account the overlap of ZUS titles and the settlement with the salary from employment.