I put 1 for W4 Personal Allowance, but I think I qualify for 2. Should I fix it with another W4 or its going to be taken care of at the time of filing taxes?

[berat]

I am a single male and only have one job at the time. When I filled W4 for my new job I only put 1 for A and a lot of tax is being taken from my paycheck. I have received several paychecks with this W4. 

However, because "I am single and have only one job;" I can put 1 in B as well. So it necessary to file another W4 or it can be taken care of when I'm filing my taxes?

[Opus 17]

Your actual tax owed is always computed on the form 1040 (or 1040-A or 1040-EZ) in January.  The W-4 is used to estimate your tax so it can be withheld correctly.  Claiming more allowances results in less withholding and more take home pay, and claiming fewer allowances means more withholding and less take home pay.  But it all gets squared up on your tax return.  If you had too much withheld, you get a larger refund.  If you did not have enough withheld, you owe.

Generally, if you go through the W-4 instructions carefully, most people should get a modest refund.  By claiming one less allowance than you could have, you had more withheld, so you should expect a larger refund when you file in January or February.

[berat]

Thank you for your response. So I don't need to go for the hassle of filing another W4 with my current employer? Hopefully TurboTax has features to take these into account?

[Opus 17]

That depends on what you want to accomplish.  Each allowance you claim will increase your take home pay by around $12-$20 a week (depending on your income) and reduce your refund by the same amount.  If you want a larger refund and less take home, claim fewer or zero allowances.  If you decide your refund this year is way too big, then you can file a new form and claim more allowances so you get a smaller refund but more take-home in each paycheck.

[SweetieJean]

Try this tool:
https://turbotax.intuit.com/tax-tools/calculators/w4/