I've been asked for my YTD salary and pay period for 2017. I've never been asked that before. Why I am being asked that this year?

[hbl3973]

Sounds like you are in an optional withholding and/or estimated tax planning dialogue. Some taxpayers will be getting a rather large refund in April rather than a modestly larger paycheck during the year. For some this is a conscious decision of forced savings and they can skip over/out of this dialogue.  Others, however, may well want to adjust their W-4 entries to avoid giving the government such a large interest-free loan.

The other class of taxpayers who might want to adjust their withholding are those with significant income outside their paychecks such as interest and dividends.  They are subject to possible underpayment penalties and/or interest unless they pay more tax throughout the year via W-4 withholding or separate 1040-ES estimated tax payments.