Hi,
To play it safe, file as Single or Married, but withhold at the higher Single Rate, to cover the risk of under-withholding and always feel free to include additional withholding tax on W-4 Line 4c, if your comfortable by additional withholding tax. You can use your prior year tax payment due as a possible guide by dividing that amount by the number of pay periods you incur annually. Only use this method if your income and deducitons are expected to be similarly the same or use a small amount to start off with as a precaution.
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