Whether we acknowledge it or not, the overwhelming majority of the Shia world today is failing in our obligation to pay Khums. Those few of us who do are inconsistent and irregular, and usually ignorant of the law of jurisprudence applicable to the proper extraction and disposal of Khums.
Let us look at the importance paid to the issue of Khums by the Holy Prophet and his Ahlul Bayt (peace be upon them). The Messenger of Allah is narrated to have said, "The curse of Allah and his angels and all mankind is upon one who consumes even one dirham from our wealth." Similarly, when Imam Muhammad al-Baqir (peace be upon him) was inquired about the smallest sin that could lead one to hellfire, he replied, "Whoever consumes one dirham from the wealth of the 'orphans' will surely enter the fire of hell. And verily, we are the orphans." Numerous other narrations attribute the consumption of forbidden sustenance (i.e. wealth upon which Khums hasn't been paid) as cause for the rejection of our Du'as and our inability to protect ourselves from sin.
As Shia Muslims, we must also understand the social and political significance of Khums. Fourteen hundred years of Muslim history is filled with corrupt and greedy Shaikhs and Muftis who ate from the government's platter and gladly rubberstamped their masters' every un-Islamic whim, from allowing pervert caliphs to marry their stepmothers and stepsisters to signing the death warrant for the grandson of the Prophet. Even today, the imams and religious leaders over the entire Muslim world are financially dependent on their governments and absolutely terrified to say anything that might jeopardize their next paycheck.
In contrast, the institution of Khums has given the scholars of the School of Ahlul Bayt a distinct fiscal independence from kings and emperors. By not having to rely on governments for financial backing, our scholars were and are able to maintain a firm commitment to honesty and truth without fear of economic retribution. It is precisely this Khums money that is overwhelmingly responsible for the majority of the hundreds of books written, the dozens of scholars trained, and the scores of mosques, Islamic centers, orphanages, libraries, and welfare centers built every year in the Shia world.
Furthermore, paying financial tribute has historically been a way of expressing political allegiance. By withholding religious taxes from corrupt and illegitimate caliphs and kings, we are affirming our faithfulness and loyalty to the Imams of the Ahlul Bayt, to whom political authority truly belongs, and in their absence, to the Maraja Taqleed (Religious Authorities) they appointed as guardians upon us. In essence, Khums symbolizes the monetary expression and proof of our allegiance to Fatima and the Children of Fatima.
For those of who are fortunate enough to pay Khums, it is vital to make sure we are consistent and diligent in doing so. Instead of being haphazard and using our personal judgment, it is obligatory upon us to learn the laws of jurisprudence regarding Khums and act accordingly. For example, many of us are unaware that Khums is not just due on monetary savings; in fact, Khums is also applicable on items and objects that were purchased but remained unused for an entire year. Furthermore, it is of the utmost importance to ensure we give our Khums to the right people. Hundreds of individuals and organizations might have permission to collect Khums, but according to Ayatollah Sayyid Ali Sistani, your Khums is not considered accepted unless the individual or organization to which you pay can provide you with a receipt signed and stamped by his office.
For those of us who have never paid Khums, it is absolutely imperative to begin right away. In this technologically advanced age, it is quite easy to obtain your financial records and account histories from banks and other institutions. The first step is to contact your Marja or his representative, and he can help you sort through your past financial history, estimate the amount of Khums you owe, and come up with a payment plan. Scholars also recommend setting an annual Khums Day and using that as the marker to calculate the Khums you owe each year. (For a detailed discussion on these various technical matters, please refer to Khums: the Islamic Tax by Sayyid Muhammad Rizvi, available online.)
On a final note, let us recall the story of the famous Bibi Shatita of Nishapur, which very beautifully demonstrates to us the high rank of one who is diligent about his/her financial obligations to the Ahlul Bayt. This poor but devout woman lived in the time of Imam Musa al-Kadhim (peace be upon him). When she dispatched her Khums to the Imam one year, she was mocked by others because the entirety of her Khums amounted to a single handkerchief. Yet she remained steadfast and said, "Allah is proud of the Truth, even if it is a small amount." When Imam al-Kadhim received it, he is reported to have looked at it and also said, "Allah is proud of the Truth, even if it is a small amount." A few weeks later, Bibi Shatita passed away. As people were preparing for her funeral, a camel rider was seen to be making his way from the direction of Medina. The people were shocked to see that Imam Musa al-Kadhim had come all the way to Nishapur to participate in the funeral prayers of this woman. When the Imam was inquired about the reason for his appearance, he replied with a powerful statement that contains a very valuable lesson for us in regards to upholding the rights of the Ahlul Bayt. "This woman went out of her way to fulfill our rights," the Imam said, "therefore, we will go out of our way to fulfill her rights."