To determine how many allowances to claim, you need to consult the W-4 guidelines. Your recommended allowances are based on items such as your status as head of household, your marital status and the number of dependents you claim. The fewer allowances you claim, the more taxes will be taken from your paycheck. At the end of the year, if you have claimed fewer allowances than you were entitled to, you will likely have overpaid and may be due a tax refund.
If you prefer to claim the maximum allowances you believe you are entitled to, you will likely have less income taken from your paycheck each month, but may find that you owe taxes at the end of the year or are entitled to less of a refund.
Your decision about allowances depends on your financial preferences and planning ability. If you prefer to maintain control over more of your income and invest it so that it earns interest throughout the year, you may want to claim your maximum recommended allowances. If you choose this path, be sure that you have earmarked some of your earnings for any taxes you may owe. If you prefer paying more throughout the year and potentially receiving a refund, you must claim fewer allowances.