These cards can help business owners get cash back and discounts on supplies and services. By Joan Goldwasser, Senior Reporter April 17, 2012 Credit cards often serve as a crucial source of funding for small businesses. Using a dedicated business credit card instead of a personal one simplifies tracking business expenses and prevents the problem of commingling business and personal purchases and then omitting deductible business expenses on tax returns. For start-ups, it also helps prove to the IRS that an enterprise is an actual business rather than merely a hobby. SEE ALSO: The Kiplinger Small Business Center Business credit cards often come with helpful tools, such as American Express’s AdManager, which helps businesses create and measure the results of online advertising campaigns. Card issuers may also offer mobile and online software to help track, organize and categorize spending. Before applying for a card, decide whether you intend to carry a balance or pay off all charges each month. If you expect to keep a balance on the card, look for one with a low interest rate. The NASA Federal Credit Union (www.nasafcu.com) -- which anyone can join by becoming a member of the American Consumer Council, a non-profit, pro-consumer organization -- offers a no-fee Platinum Business credit card with an interest rate as low as prime plus zero, or 3.25%. To become a credit union member, you open a savings account with a $5 deposit. The no-fee Wells Fargo Business Platinum card, the Bank of America Platinum Visa Business card and the Platinum Plus for Business MasterCard all have an interest rate of prime plus 5.99%, or 9.24%, if you qualify. Advertisement Just rewards. Because rewards cards often have higher interest rates, they usually make sense for people who pay off their entire balance each month. If you carry a balance, the amount you would pay in interest could offset the rewards you earn. Business rewards cards include cash rewards, airline miles and hotel stay cards. Here are a few of the best cash-back cards: --American Express’s no-fee SimplyCash card offers 5% cash back on wireless phone charges and office supply purchases, 3% on gas purchases up to $12,000 (then 1%) and 1% on everything else; rewards are credited automatically on the monthly statement. It has a 0% introductory rate on purchases for six to twelve months; after that, the rate jumps to 12.24% to 19.24%, depending on your creditworthiness. --Chase offers Ink Cash, a no-fee card that gives you a 5% rebate on office supplies, phone (including wireless) and cable services, 2% on gas purchases up to $25,000 and 1% on everything else. It has a 13.24% interest rate after a six-month 0% introductory rate. -- You receive a 2% cash rebate on all spending with no cap with the Spark Cash Business credit card from Capital One (13.95% interest rate). Its $59 annual fee is waived for the first year. The no-fee Spark Cash Select Business credit card (14.9% to 19.9% rate) gives you a 1% cash rebate plus a 50% end-of-the-year cash bonus. So if you spend $25,000 and earn $250, you’ll receive an additional $125 at the end of the year. Advertisement If a card that rewards you with a discount for prompt payment appeals to you, check out the Plum Card from American Express. It gives a 1.5% discount to business owners who pay in full within ten days of the end of the billing cycle. Or you can take two months to pay without owing any interest or finance charges. What to watch out for. The protections of the 2009 Credit Card Accountability, Responsibility and Disclosure (CARD) Act apply only to personal cards. Some issuers, such as American Express and Bank of America, have voluntarily adopted some of the law’s provisions for their business cards -- such as giving cardholders 45 days’ advance notice of rate changes for future balances and providing a grace period of at least 25 days from the statement closing date to the due date. Be aware that card issuers often report late payments on business cards to the owner’s personal credit file. Chase normally reports to a commercial credit bureau, but delinquencies past 60 days will go on the owner’s personal credit report.