Register for NIP (Tax Identification Number): As a sole proprietor, you'll need to obtain a NIP, which is a tax identification number. You can apply for this at the local tax office (Urząd Skarbowy) or online through the Ministry of Finance website.

Register for REGON (National Business Registry Number): You may also need to obtain a REGON, which is a statistical number assigned to businesses in Poland. This can also be done at the local tax office or online.

Choose a Legal Form: Since you're opting for a sole proprietorship, you'll operate as an individual rather than a separate legal entity. However, you might still need to specify your business activity.

Register with the Central Register and Information on Economic Activity (CEIDG): This is the main register for sole proprietors in Poland. You can register online through the CEIDG website or submit the necessary forms in person at the local CEIDG office.

Obtain Necessary Permits and Licenses: Depending on the nature of your contracting business, you may need specific permits or licenses to operate legally. This could include construction permits, health permits, or professional licenses, among others.

Open a Business Bank Account: It's advisable to separate your personal and business finances by opening a dedicated business bank account.

Comply with Tax Obligations: As a sole proprietor, you'll be responsible for paying income tax on your business profits. Ensure you understand your tax obligations and keep accurate records of your income and expenses.

Consider VAT Registration: Depending on your expected turnover, you may need to register for VAT (Value Added Tax). This is mandatory if your annual turnover exceeds certain thresholds, but you can also voluntarily register for VAT even if you're below the threshold.