What is the salary of a Catholic priest?
The salary of a Roman Catholic priest depends upon many factors. In the United States, the first major factor is whether the priest is a diocesan (secular) priest or a professed (order) priest. Diocesan priests who live "in the world" and generally are responsible for taking care of parish churches receive a salary from their parish to keep for personal use (savings, retirement, automobile, vacations, charity, etc.). The diocese will set this salary and usually there will be a multiplier or other incentives for years served, the size of the parish, the oversight of a Catholic school, or other factors. In the U.S., priests pay taxes on this salary as everyone else does. (Actually, priests pay more than their share as they have to pay both halves of social security... strangely enough, they are 'employees' with respect to federal and state taxes, but 'self employed' with respect to social security.)
Individual dioceses also have policies which restrict a priest's right to receive any further remuneration from their ministerial activities (Masses, baptisms, weddings, funerals, etc.). Often these 'stole fees' are directed solely to the parish in order to pay the priest's regular salary. Often, priests are only allowed to keep gifts from ministry activities which are explicitly specified as personal gifts.
Priests generally will also receive housing or a room-and-board allowance (which they also pay taxes on), a professional allowance (books, subscriptions, retreats, and conferences), health insurance, a pension, and perhaps other allowances (depending on the diocese: mileage, auto, insurance, moving expenses, etc.) In very exceptional cases where a Roman Catholic priest might have a family or dependents (yes, this is possible), provision is usually made for a living wage on a case-by-case basis with the priest's bishop.
Order priests may also receive a salary, but as they are vowed to poverty, they are not allowed to keep the salary for their own use. Any salary they receive is put into the common fund of their religious community. If they need anything, they may receive an allowance from their parish or their community according to their needs and the particular discipline of the community.
Law obliges the Church to provide for the basic necessities of all priests (religious or secular) when both 'active' and in retirement. A priest who is not bound to community life may chose, at his own expense, to live at a higher standard (in his own apartment, home, or retirement community, etc). The only way that a priest may lose these benefits is to be dismissed from the clerical state (either voluntarily by leaving or perhaps involuntarily as a consequence of being removed). One of the provisions of the "Dallas Charter" regarding the sexual abuse scandal in the U.S. is that priests who abuse minors are to have their cases sent to Rome to have the priest dismissed (often involuntarily) from the clerical state, or "laicized". Thus, as a result of laicization when applied as a penalty, these 'former' priests are no longer entitled to any support from the Church.
Priests may have 'extra' sources of income, such as a position teaching in a school or college, or income from other academic pursuits (book royalties, speaking engagements, etc). They may receive an income for military service or chaplaincy elsewhere. If they had a previous career, they can receive retirement benefits from this. They may also receive or inheirit wealth from their family. There is a Canon in Law which prohibits priests from owning or running an outside business without their bishops (or other superior's) permission. Whether the priest keeps this income depends, again, on whether the priest is 'secular' or 'order'.
Catholic priest salaries are very low compared to other professionals who spend at least 8 years in post-secondary education. Whether vowed to poverty or not, priests are to live a life without an excessive concern for the goods of this world. A typical monetary compensation package for a parish priest in the U.S. might run somewhere between $15k-30k (before taxes) with health insurance and a pension included. Bishops often take a salary commisurate with that of a similarly-tenured priest, with other provisions made by the diocese for the greater expenses of episcopal ministry (travel, vesture, office, etc.).
It is a most laudable practice and a good example to their people for priests who do receive a salary or other income to tithe to their own parish and/or to their diocesan operating fund.
The answer to the question depends on the type of priest, and his assignment. There are two types of priests: Religious Order Priests and Diocesan Priests. Religious order Priests are priests who are part of a religious order, such as the Jesuits. They take a vow of poverty and do not directly receive a salary. They receive a small monthly stipend perhaps of 100 dollars to take care of personal expenses. The institution they work for will pay out a salary for the work they perform, but that salary is paid to the community.
Diocesan Priests are priests who are ordained for a particular Diocese. Another name for them is "Secular Priests" because unlike religious order Priests they live and work in the secular world among their people. They do not unlike religious order priests focus on one specific ministry such as teaching, or hospital work, but rather do every kind of ministry.
Diocesan Priests do not take a vow of poverty, though many people erroneously attribute such a vow to them. They receive a set salary just like everyone else for the work they do.
The salary of a Diocesan Priest usually ranges from between 15K a year at the low end to 30K a year at the high end. If we add in the stipends, and the fact that priests do not pay rent for housing, the range is 20K a year at the low end to 35K a year at the high end. Priests pay taxes on their salary just like everyone else, and the fact that they receive housing from the parish is considered income. Thus priests must pay taxes on that as well. Each priest must "impute" the worth of the housing on their income taxes. Thus, if the going rate in the area where the priest lives is 500 per month, the priest must "impute" 6K a year to their taxes as income even though they do not receive 6K a year in real cash.
Priests also receive like most people a health care package. The salary for the priest comes from the priest's assignment. If a priest is assigned to work for the Diocese in some capacity, the Diocese assumes the cost of the priest's salary. If a priest is assigned to a parish, the parish assumes the cost. If a priest is assigned to a school the school assumes the cost. If a priest is assigned to a parish and school, or pastors more then one parish, the salary is split between the assignments. Priests in general do not get paid extra for taking on extra assignments, though I speak generally. Each diocese sets their own policy, and each diocese sets the salary of a priest.
There are exceptions to this as there are to everything. For example, Diocesan priests on special assignment, such as professor at a university might make the the salary of a professor. Diocesan priests assigned to the military will make the military salary for the position. Generally speaking however, the salary will range from (including stipends, housing, etc) 20K at the low end to 35K at the high end.
The above answer represents the pay grade as it is in the United States of America.