Taxes and rates changed back in March 09). If your employer followed the NEW rates (according to the Presidents new tax relief fund) LESS taxes were taken out of everyones pay, but NOT by much like maybe a dollar or so. This also depends on the state you are in too. I would start by checking your W-4 status with your employer for your state and make sure they are withholding the correct amount. If they didn't then you will have the same problem this year. (first off) You can actually TELL your employer to withold any amount you want. For example: If you are Married, claiming 1 and you make $500 a week, paid weekly and the state tax table says withhold $35.00 - and you think that may not be enough to cover you at the end of the year you can ask your employer to OVER RIDE that amount and have them withhold MORE. It's not a common practice, but it's perfectly legal. Better than trying to pay more at the end of the year.
Also if you are not sure and do NOT want to ask your employer? You can take your paystubs to ANY state office or branch of the tax office and they will check for you or you can order a book/publication and do it yourself. Most times the tax tables are published on line for each state.
H&R block is not my favorite for taxes. I used to have them do my taxes and then one year they cost me a LOT of money - fortunately I purchased their very expensive insurance and they had to redo my taxes. After that? I found individual firms a lot more willing and up on the newest breaks and deductions because THEY do it year round. Most (not all) but MOST HR Block and Jackson Hewitt and places like that start advertising for employees in December to work their tax season, NOT all year long. Something to keep in mind. I've used Tax Slayer on line (free for federal $15 for state) for the last 5 years and I've been very happy with them) Their software is very up-to-date on current laws, deductions, etc. They even let me do long form last year and found stuff for me to deduct I had no idea I could deduct.