Mortgage underwriters normally want documentation attached to the letter of explanation. For example, a letter of explanation may be required if a mortgage loan borrower had a substantial low income one year from the previous year and had a late payment history for three months.
Wage garnishment by itself will not damage your credit...and the fact that your wages are being garnishment will not be noted on your credit report....However, the judgment that led to the garnishment (if they report it) will affect your credit rating...and the original default of your credit card will also still damage your credit rating.
Illinois law allows creditors to take 15 percent of your gross wages. This doesn't, however, mean that such a high percentage is mandated. Further, if you have multiple garnishments, the total amount of the garnishment can't exceed 15 percent. For example, a credit card garnishment of 10 percent of your wages would mean that a second credit card garnishment could be no more than 5 percent.