The obligation to contribute is considered to be the cost that the taxpayer submits in cash for his personal insurance or which the taxpayer pays in favor of another person - the insured. The period spent in insurance and on the basis of insurance is an obligation to calculate and pay contributions. Contributions are calculated on a monthly basis that represents the income received or salary in a certain period of time. In this paper, is defined and present the application of the lowest and highest monthly base for the calculation of contributions in 2021, determined by the Law on Contributions. The basis for calculating the minimum and maximum monthly basis for calculating contributions is the average gross salary per employee from the previous year in the period from January to August. The lowest monthly base is calculated by increasing the average gross salary for 2020 by the statutory coefficient -HRK 9,181.00 x 0.38 which amounts to HRK 3,488.78. The highest monthly base is the product of the average gross salary and predicted coefficient - HRK 9,181.00 x 6.0, which amounts to HRK 55,086.00. The maximum monthly base limits the payment of I. (contribution based on generational solidarity) and II. (contribution based on individual capatilized savings) pillar. To create examples of spreadsheets and, finally, to fill in the JOPPD forms of pages A and B all official forms were used and laws were followed and regulations currently in force.