Umowa o pracę, umowa o dzieło and umowa zlecenie
Umowa o pracy is a full contract of employment, umowa zlecenia is temporary. Both have tax and National Insurance deducted at the appropriate rate. Umowa o dzielo is a freelance contract for specific work done. It is taxed at the basic rate minus a small allowance for your (real or otherwise) expenses. There is no National Insurance taken from it; you are responsible for this yourself.
Can you tell me what these deductions refer to:
Taxation, Health insurance, insurance and pension credit?
Taxation is what you would expect it to be. Health insurance, insurance and pension credit are the three components of National Insurance. You have to pay it all, however you can opt for the pension part to go into a private fund of your choice. This is usually a good idea but whichever you choose, the amount you have to pay is the same.
In general what coverages does a compensation package include?
Your salary. This is Poland not Dubai.
In Poland for somebody working in private company as an employee, how many salaries per year is he entitled to 12 or 13?
12. Payable on the last day of each month.