Spouse worked part of the year

[vk1]

Here is my scenario.

So far I am claiming my wife as dependent and got tax benefits.

If my wife starts working from next month, Do I need to pay tax for entire year and return amount I benefited so far  this year.

[xmasbaby0]

You do not “claim” a spouse as a dependent.  By filing as “Married Filing Jointly” you will each get the $4050 personal exemptions and the standard deduction of $12,600 for a married couple.  (In 2017 it will be $12,700)

You can file a joint return even if one of the spouses had little or no income.

If you were married at the end of 2016 your filing choices are married filing jointly or married filing separately.

Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will each receive the $4050 personal exemption, plus the married filing jointly standard deduction of $12,600 (add $1250 for each spouse over the age of 65).  You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit. 

If you choose to file married filing separately, both spouses have to file the same way—either you both itemize or you both use standard deduction. Your tax rate will be higher than on a joint return. Some of the special rules for filing separately include: you cannot get earned income credit, education credits, adoption credits, or deductions for student loan interest. A higher percent of your Social Security benefits may be taxable.  In many cases you will not be able to take the child and dependent care credit. The amount you can contribute to a retirement account will be affected. If you live in a community property state, you will be required to provide additional information regarding your spouse’s income.  If you are using online TurboTax to prepare your returns, you will need to prepare two separate returns and pay twice.

https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately

[xmasbaby0]

@vk Upon re-reading your question, it appears that you are actually talking about the way your W-4 was set up for your employer for the amount that would be withheld from your paychecks.  You were claiming an exemption for your spouse and getting the "benefit" of a somewhat larger amount of take-home pay than if you had not claimed that exemption.  Your W-4 is only for your employer, and does not dictate how you have to file your tax return.  Now your spouse is going to be working, too.  When you file your joint return, your refund or tax due will be based on the total of your combined earnings.  If you have had too little withheld, you could owe; if you have had more withheld than your tax liability then you will get a refund.  Going forward, you and your spouse could take a look at your tax situation by using the tax caster tool.  You can also use the W-4 calculator to determine if you should now stop claiming the exemption for your spouse on your own W-4, or if she should just have some extra tax withheld from her own paychecks to prevent you from owing at tax time.  You can change your W-4 even in mid-year.
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