Money laundering is the process of concealing the source of money obtained by illicit means. The methods by which money may be laundered are varied and can range in sophistication. Many regulatory and governmental authorities quote estimates each year for the amount of money laundered, either worldwide or within their national economy. After Skyler White discovers that Walter White was involved in the drug business, she soon decides to aid Walt to launder all the earned money through the A1A Car Wash business.
Walt and Skyler use the "structuring" method, which is a method of placement by which cash is broken into smaller deposits of money, used to defeat suspicion of money laundering and to avoid anti-money laundering reporting requirements. A sub-component of this is to use smaller amounts of cash to purchase bearer instruments, such as money orders, and then ultimately deposit those, again in small amounts.
Gustavo Fring also uses this method with his fast-food restaurant chain Los Pollos Hermanos. Though this was less obvious as the chain had a larger structure and was theoretically possible to be making large amounts of money.
As Walt begins to earn more and more cash, he soon discovers that he cannot spend the money without his family growing suspicions of his drug business. Saul Goodman then aids Walt by sending small, but consistent "donations" through Walter White Jr.'s website SaveWalterWhite.com with the help of one of Saul's computer hacker friends ("Mandala").
After Skyler discovers that Walt was involved in the drug business, she soon begins to take great interest to launder his hard-earned money. Skyler begins to research about money laundering and consults Saul for advice on the matter. Saul recommends Skyler and Walt to invest in a laser tag business, which Skyler and Walt ultimately deny ("Abiquiú"). They then decide invest in the car wash business.
Skyler employs her book-keeping skills to settle a domestic issue to purchase the car wash from Bogdan Wolynetz. This ultimately succeeds and the car wash was purchased. After a brief celebration, Skyler and Walt decide to come up with a cover-up story to tell Hank Schrader and Marie Schrader when they come over for dinner ("Bullet Points"). The laundering process then begins and Skyler officially became the owner of the car wash.
After Gustavo Fring's death, Walt begins to press on his drug business by cooking meth at greater amounts. Walt soon finds a distributor from Mike Ehrmantraut's old time associates and the money begins flowing at even greater amounts. After too much money had been laundered, Skyler moved all of the money to a rented storehouse to avoid suspicion ("Gliding Over All").