Just married. Both employed. Plan on filing jointly for 2017 tax year. What would be the recommended update to our W-4s to ensure we end up receiving a refund?

[Carl]

Don't change them at all. Just leave your W-4 you presently have on file with your employers exactly as it is. If you've individually been getting refunds in the past, then you will most likely continue to do so in the future, filing joint.

[TaxGuyBill]

I agree.  Most newlyweds immediate change their W-4s to "Married", and get shocked when they owe money.  Keeping it as "Single" (or "Married but withhold at the higher Single Rate"), usually works out well.

[Opus 17]

To see what the IRS recommends, you would fill out the worksheets on both sides of the W-4 form (for two jobs, and taking into account your deductions and dependents).  That gives you a number of allowances you can claim.  You don't each claim them -- you divide them between you.  So if you have 4 allowances on the worksheet, you might give your employers new W-4 forms that claim 2 each, or one person 4 and one person zero.  If you want a larger refund, claim fewer allowances (you will see a dip in your take home pay of course).

For an accurate estimate now (based on not changing anything) use this calculator.  It requires detailed input but will give a detailed and correct answer. https://www.irs.gov/individuals/irs-withholding-calculator

You can also use the calculator if you change your withholding, after you get the first couple of paychecks with the new withholding.

I also agree that if you simply leave things alone, you will probably get the same or a larger refund.  Your W-4 does not have to match your lifestyle (# of dependents, married, etc.).  It is just a tool for determining your tax withholding and does not have to match your tax return.