Susan Tompor

Detroit Free Press Personal Finance Columnist

Opening Day for the IRS is Monday.

That's when the Internal Revenue Service will start accepting electronically filed tax returns. We have until April 18 to file returns but many file earlier in the season, if they're expecting large refunds.

The tax filing deadline this year is Tuesday, April 18, instead of the traditional April 15, because of some quirks of the calendar. April 15 is a Saturday. But the deadline won't be shifted to Monday, April 17, because that is Emancipation Day, which is celebrated in Washington, D.C.

What do tax filers need to know this season?

1. Get an appointment if you want to talk to someone at IRS offices.

Don't expect to drop into an IRS office to get any help this tax season. All offices are appointment-only now.

If you need to visit an IRS Taxpayer Assistance Center in person, you must schedule a time by calling 844-545-5640 for the appointment hotline.

Taxpayers are asked to check IRS.gov for the days and hours of service, as well as the services offered at the location they plan to visit.

More on taxes:

Fast-cash options offset expected delay of tax refunds

Some families can't bank on a tax refund before Feb. 27

More W-2s to have a 16-digit code to fight tax fraud

2. Beware of a new hurdle if you've used a special Individual Taxpayer Identification Number.

Some tax filers will be unable to file their federal tax returns if they do not update Individual Taxpayer Identification Numbers. Warning: Any ITIN that has not been used in the past three years will no longer work for filing that return.

On top of that, individual tax identification numbers that have middle digits of 78 or 79 also expired this year.

Tax filers in these situations must renew an Individual Taxpayer Identification Number as early as possible because they cannot file a tax return without one.

The super-sized headache? The IRS notes that it can take up to 11 weeks during the peak of the tax season to get that number from the time you send in a renewal application, known as Form W-7, for the IRS to process the application and notify you about your status.

Why the change? A new federal law to combat fraud included the requirement that certain Individual Taxpayer Identification Numbers expired on Jan. 1.

"Anyone filing a tax return with an expired ITIN could experience return processing and refund delay as well as denial of some tax benefits until the ITIN is renewed," the IRS said online in a statement.

These identification numbers often are used by people who have tax-filing or payment obligations under U.S. law but are not eligible for a Social Security number.

3. Some struggling families will face delays for their tax refunds.

The IRS notes that more than nine out of 10 refunds will be issued within less than 21 days, which is good news.

But tax filers who benefit from the Earned Income Tax Credit and the Additional Child Tax Credit should not expect their refunds until possibly the week of Feb. 27, even if they file as soon as this week.

The reason? Congress is cracking down on tax-return related fraud. The Protecting Americans from Tax Hikes Act mandated the IRS delay issuing tax refunds for returns claiming the EITC or the Additional Child Tax Credit until Feb. 15. The move is designed to give the IRS more time to detect fraud and prevent refunds from being issued to ID thieves who file fake tax returns using such credits.

But consumers who depend on the refund cash will face extra delays, given holidays and weekends.

Another thing to note: The IRS online "Where's My Refund" tool will not show an estimated date for many tax returns involving the special credits until after Feb. 15.

"So don't panic in late January and mid-February if you don't see a refund date on 'Where's My Refund.' That's just how the tool will operate given the special circumstances with the EITC and ACTC refunds," said IRS Commissioner John Koskinen in prepared remarks in early January.

"Where's My Refund" at www.irs.gov and the IRS2Go phone app will be updated a few days after Feb. 15 with projected deposit dates for the early filers who receive the earned income credit and additional child credit.

More from Susan Tompor:

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4. Look out for high-cost, quick-cash on tax refund advances.

Tax filers might be tempted by refund anticipation loans that proclaim "no fee" will be charged. But Chi Chi Wu, staff attorney for the National Consumer Law Center, warns that in some cases, borrowers could face other higher fees for tax preparation or another product.

Advance loans are being heavily marketed this year by some firms, including H&R Block and Jackson Hewitt, in light of the new delays ahead for tax refunds for those who file those Earned Income Tax Credit and the Additional Child Tax Credit.

Jackson Hewitt is marketing for its Express Refund Advance, a loan of up to $1,300 that has no fees, a 0% annual percentage rate and no credit check. To get the loan, you will have to pay to file your taxes with Jackson Hewitt.

H&R Block began offering a tax-related loan for a limited time beginning Jan. 6. The H&R Block Refund Advance offers loans in the amounts of $500, $750, or $1,250 upfront for 0% interest.

The loan is loaded onto an H&R Block Emerald Prepaid MasterCard.

The amount of the advance will be deducted from tax refunds and reduce the amount that is paid directly to the taxpayer. Both Jackson Hewitt and H&R Block only offer the loans to customers who visit their offices and outlets; it's not available online.

5. Take a close look at that W-2 Form.

Some tax filers are going to discover that they have to deal with a "Form W-2 Verification Code."

About 50 million W-2 forms will include a 16-digit verification code that tax filers or preparers will need to add when prompted by tax software. About 2 million W-2s had such a code during the 2016 filing season.

The IRS anticipates that the verification code ultimately will be used on all W-2 forms in future years.

Again, we're looking at another hurdle to try to corral the crooks and prevent the filing of fake tax returns.

6. Remember, scam artists love tax season.

"We continue to ask the public to be vigilant because the scamming doesn't stop," said Luis D. Garcia, IRS spokesperson in Detroit.

The con artists pretending to be from the IRS might reach out via your e-mail in-box, your mailbox or even knock on your front door, Garcia said.

And the crooks are going after tax preparers, too.

Earlier in January, the IRS warned that cyber criminals were pretending to be tax filers who wanted help filing their returns.

The first e-mail says something like: "I need a preparer to file my taxes."

If the tax preparer responds, a second e-mail is sent that has either an embedded web address or contains a PDF attachment that has an embedded web address.

"The tax professional may think they are downloading a potential client's tax information or accessing a site with the potential client's tax information," the IRS warned.

"In reality, the cyber criminals are collecting the preparer's e-mail address and password and possibly other information."

Oddly enough, I even got one of these phishing e-mails last week. The language was stilted and off-kilter, which can be a warning sign.

It began "Hello, CPA," which I am not.

"I need a careful and experienced high quality accountant, to handle all matters of accounting including tax preparation, IRS problem resolution, and matters expected of a CPAs to handle for Individual and Small Business," the e-mail read.

"I don't need that stereo typically dull, introverted and boring accountants, I believe in the value of partnership in business relationships."

"Find attached is my tax documents."

Love that last line. I'd love to respond: Find this attachment for a way to learn how to diagram sentences and master subject-verb agreements.

But then again, we don't want the scammers to get even better at this game, do we? Best to kill and ignore all such phishing e-mails.

Contact Susan Tompor: stompor@freepress.com or 313-222-8876. Follow Susan on Twitter @Tompor.