Still, filers in both groups can take advantage of this year's basket of Tax Day rewards, including free pizza and cookies and hotel and getaway discounts. CNBC took a look at some of what's being offered to help soothe the IRS jitters.

Millions of taxpayers are still rushing around gathering receipts, and grappling with paperwork, days before Tuesday's filing deadline. Millions of others have already received refunds.

Grimaldi's Pizzeria locations around the country are offering 16" traditional cheese pizzas for $10.40 (inspired by the individual filing form). Bruegger's Bagels is offering a downloadable coupon for a Big Bagel Bundle (13 bagels and two tubs of cream cheese) for $10.40 — a $3.50 "deduction" off the regular price, and valid through April 17.

In keeping with its rallying cry of "No taxation without relaxation," Kona Ice trucks will hand out free shaved ice on Tuesday. Hardee's "Tastes Like America" menu campaign will offer customers a free Sausage Biscuit until 10 a.m., and Hot Dog on a Stick will give every customer who stops by participating locations one free Turkey or Veggie Dog.

On Tax Day ( April 17 this year), Great American Cookies will be giving away a free cookie to anyone who stops at one of their participating stores. This year's treat is Cookies & Cream.

This month, anyone who downloads the app for Potbelly Sandwich Shops and joins its Potbelly Perks program will get a free sandwich. Those already enrolled in the program will find a buy-one, get one-free sandwich offer loaded on their app April 17 for Tax Day use.

Travel Deals

Throughout the month of April, four Kimpton hotels in Southern California — the Palomar and Salomar in San Diego, the Shorebreak in Huntington Beach and The Goodland in Santa Barbara — are giving out "Random Refunds." Each day, a randomly chosen guest at each hotel will be refunded a hotel charge such as the resort fee, parking charges, restaurant bill or the in-room movie.

From April 17 to 20, Michigan's Hotel Saugatuck is offering a 20 percent discount to any independent worker who shows a current 1099 tax form (or proof of membership in the United Auto Workers or Freelancers unions). The bed and breakfast is also offering guests a box of local chocolate fudge at a discount, for $10.99.

Thinking of spending your tax refund in Europe? Rail Europe is offering travelers $25 off for $400 bookings made through April 24. Use code: TAXDAYRE18.

Budget-minded tax filers can also take advantage of some other timely travel deals that just happen to fall around April 17.

Filing taxes may not be a walk in the park, but anyone can take a walk in the National Park for free on Saturday, April 21. On that day, entrance fees will be waived at any of the parks that have them, including Mesa Verde National Park in Colorado, Arizona's Petrified Forest National Park.

The U.S. Travel Association's Daily Getaways sale runs this year through May 8, and will feature daily deals up to 60 percent off. The special includes everything from loyalty point programs and car rental coupons to attractions tickets and hotel stays, courtesy of brands like Hertz, Hilton and Universal Parks and Resorts.

Disclosure: NBCUniversal is the parent company of Universal Studios and CNBC.

— Harriet Baskas is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas. Follow Road Warrior at @CNBCtravel.