To get the Back Taxes achievement, you need to find the hidden prize in every episode. The prizes are found by answering the "Wrong Answer of the Game" in each episode. These wrong answers have to do with the sponsor clue that is in the title of the episode.
When selecting an episode, if there is a small picture of a gift box next to the title, then that means you have already gotten the prize in that episode.
Once you get the prize during the episode, you need to finish the episode for it to save you getting it, otherwise it will not count if you quit.
If you are playing multiplayer, and get screwed by another player, you will not get the prize by answering the wrong answer of the game. All that will do will prevent other players from selecting it.
Here is the list of each episode with name and the question number and wrong answer that will award you the prize of that episode.
Episode 1: Supreme Court Children's Vitamins
8-Y
Episode 2: Fistable Bowling Equipment, Inc.
2-A
Episode 3: Buoyant Baby Water Cribs
9-Y
Episode 4: Fat-Mouth Facist Fish
8-A
Episode 5: Fashion Barrel Barrel Wear
9-A
Episode 6: Romanticlip Toenail Clippers
4-B
Episode 7: Granny's Roach Butter
2-Y
Episode 8: Brownana Banana Toasters
6-X
Episode 9: Hopalong Harry's One-Leg-AT-A-Time Pantorium
6-A
Episode 10: BloodCo.
4-X
Episode 11: Country Charm Indoor Outhouses
5-B
Episode 12: The Girly Drink Supply Warehouse
3-A
Episode 13: You've Got Gall! Gall Stone Jewelers
10-X
Episode 14: What-a-Prick Cactus Company
7-Y
Episode 15:Rug Munchers Dietary Flooring
3-B
Episode 16: Grin Toothpaste Kegs
6-X
Episode 17: Digitensils Electronic Utensils
5-Y
Episode 18: Crazy Oedea's Discount Amoebas
3-A
Episode 19: The Insincere Greeting Card Factory
6-A
Episode 20: Dick's Dickeys
9-Y
Episode 21: Magic Pudding
9-Y
Episode 22: Ted's Drop Dead Gorgeous Body Bags
8-A
Episode 23: Reformed Robots Housecleaning Company
2-A
Episode 24: Salvador's Unnecessary Animal Hybrids
2-A
Episode 25: No Suprise Jack-in-the-Boxes
8-Y
Episode 26: Owensville H.S. Lost and Found Outlet Store
10-Y
Episode 27: Fat Jim's Weasel Jerky
7-A
Episode 28: Burnie's Baby-Browning Tanning Beds
4-Y
Episode 29: Beautiful on the Inside Surgical Artwork
2-Y
Episode 30: Pot-O-Man Toilet Ottomans
8-X
Episode 31: Mr. Cow's Presidential Grilled Cheese Sandwiches
6-A
Episode 32: Rocky's Rodent Rockets
7-Y
Episode 33: Bobbe's Knobbe Shoppe
5-B
Episode 34: Hawaii Hal's Lava Lampshades
6-Y
Episode 35: Shaggy's Roof Carpet
4-X
Episode 36: The Internet: The Book
2-X
Episode 37: It's Never Too Late Adult Orphanage
3-A
Episode 38: Uncle Farty's Specialty Woopie Cushions
5-B
Episode 39: Betchup, The Baked Bean Sauce Condiment
9-A
Episode 40: Buzz Kill Bee Beard Trimmers
8-X
Episode 41: Ted's Wires
7-X
Episode 42: "I'm Not Dead" Coffins for the Living
10-Y
Episode 43: The Red Council
5-B
Episode 44: The Suitcase Suit Warehouse
7-B
Episode 45: The Breast Vet Cosmetic Animal Enhancements
6-A
Episode 46: Mama Leone's Pasta Beauty Parlor
9-A
Episode 47: Lawn Wax
4-Y
Episode 48: Felt-Up Hand Puppet Lube
10-B
Episode 49: Herb's Herb
2-X
Episode 50: Ultimate Control Remote-Controlled Remotes
7-Y
Episode 51: U-PLAN-IT Murder Supplies
6-Y
Episode 52: Bed-Womb Buddies
4-A
Episode 53: Vitamin Holy Water
2-B
Episode 54: Loco Louie's Breakable Party Favors
3-Y
Episode 55: Nite-Time Putty
5-A
Episode 56: Gas O' the Sea Dolphin-Fueled Cars
7-B
Episode 57: Chick-of-the-Sea Mermaid Starter Kits
5-Y
Episode 58: Jack's Bald Caps & Hairless Knick-Knacks
4-Y
Episode 59: L'il Smacky's Candy Contraband
3-X
Episode 60: Mysterious Boxes, Inc.
8-X
Episode 61: Lube Ratz Gerbil and Rodent Grease
3-B
Episode 62: Yell-o?! Pages Audio Telephone Books
2-Y
Episode 63: Safe-T Co.'s Car Darts
3-X
Episode 64: High End Leather Toilet Paper
6-B
Episode 65: Dr. Lenny's Assorted Pills
3-Y
Episode 66: Vance van Van's Van Lot
8-B
Episode 67: The Cloud Registy
7-B
Episode 68: Mee-Ow! Inappropriate Cat Accessories
7-B
Episode 69: Just Hair Hair Superstore
3-X
Episode 70: Tootie's Butt Kazoos & Anal Instruments
5-Y
Episode 71: Grammer Garments & Punctuation Pants Warehouse
6-A
Episode 72: The Grim Reaper Depot
2-A
Episode 73: Cookie Masterson's eBay Store
9-Y