Here are five tax tips that you need to know if you plan on filing your tax returns early, as well as some important land mines you probably need to be aware of.

Number one: Some families will face delays in getting their tax refunds. The IRS notes that more than nine out of 10 refunds will be issued in fewer than 21 days, which is good news. But tax filers who benefit from the earned income credit and the additional child tax credit should not expect their refund until possibly the weekend of February 27th, even if they file as early as this week. So, it could take a month to see your return. The reason is because Congress is cracking down on tax return-related fraud. If you have the earned income credit and child tax credit, then be prepared for a possible delay.

Number two: Look out for high cost, quick cash on tax refund advances. The ads are already on radio and TV. Tax filers might be tempted to take out refund anticipation loans that proclaim no fee will be charged. The reality is borrowers could face other higher fees for tax preparation or another product. Advanced loans are being marketed heavily this year with HR Block and Jackson Hewitt in light of the delays ahead for tax refunds for those who filed for the earned income tax credit and the additional child tax credit. Usually if someone is promising you a cash advance, you are going to pay somewhere. Be very cautious and if you can, wait on the money. Don’t fall victim because you are going to end up paying somewhere.

Number three: Take a close look at that W-2 form. Some tax filers are going to find that they have to deal with a form W-2 verification code. You may not know this, but about 50 million W-2 forms will now include a 16-digit verification code that tax filers will need when they are prompted by their tax software. In the 2016 filing season, only 2 million W-2s had that code. The IRS is anticipating that the verification code will be used on all W-2 forms in future years. That’s potentially another hurdle that could delay getting that return filed.

Number four: 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 their individual taxpayer identification number. For example, if you haven’t used that number in the past three years, it will no longer work in filing the return. Individual tax ID numbers that had middle digits of 78 or 79 also expired this year. So, you might hit a road block there.

Number five: Remember that scam artists love tax season. Be vigilant that con artists, pretending to be the IRS, might reach out to you via email or even knock on your front door. The crooks are going after tax preparers as well. In January, the IRS warned that cyber criminals were pretending to be tax filers that wanted help filing their returns. Be very careful about everything, especially electronic, and any solicitations. Don’t call numbers in the emails, but call the numbers of your tax preparers or the IRS directly. Get the proper numbers from their websites. Just assume that it might be real, but just in case, call the tax preparer directly or go to IRS.gov and find the correct number to make the phone call.