Brother is taking advantage of my parents. What can I do legally to try to resolve this?

Does your mother like taking care of your brother's clothes? It's not impossible that she does, you know; but if she doesn't, encourage her to tell him that she is tired of doing it and he will have to make alternative arrangements.

The utility bill: are you paying it for your parents? Why are you? Or, do you mean that you suggested that since he is getting his laundry done here he ought to contribute to the costs?

Who asked him to move the dryer? If it was your parents, and your brother refused, your parents are within their rights to toss it themselves. They should give him notice, say a week or two, and if it hasn't gone by then they have it taken to the tip. Would you be able to move it for them at their request?

Regarding the tax dodge, it is up to your parents to object to this idea and, if they suspect your brother has gone ahead with it, to report the facts to the authorities if they're minded to.

Has there been a recent change in your brother's circumstances that your parents are trying to support him through?

You asked about the legality of this. If your parents are of sound mind then what they allow in their home and with their money is their choice and there’s nothing you can do to change it. You can attempt to report the suspected tax fraud. Also a good idea to check into whether your parents have their own documents in order, such as POA’s for finances and medical, a will, advance directives, etc. so you know what the future will look like