AUSTIN — More than 700 local musicians are scheduled to perform at 230 Austin-area venues Tuesday as HAAM Day returns with its largest lineup in more than 20 years. The annual event is the signature fundraiser and community celebration for the Health Alliance for Austin Musicians, a nonprofit that helps local artists obtain affordable health care. HAAM was founded in 2005 to address a gap faced by many working musicians, who often earn income through changing combinations of gigs, teaching, recording sessions and freelance work rather than a traditional employer with health benefits. The festival’s headquarters this year will be the H-E-B on South Congress Avenue. Six other H-E-B locations will also host musicians, with performances scheduled from 6 a.m. to 6 p.m. Music is also planned at established Austin venues including Antone’s, ABGB, the Scoot Inn, Stubb’s and Radio/East. Additional performances will take place at restaurants, retail stores, coffee shops and neighborhood spots throughout the city. The scale of this year’s event highlights both Austin’s enduring live-music identity and the financial insecurity that can accompany a career in music. By linking performances with health-care support, HAAM Day directs attention to a basic need that can be difficult for independent artists to afford on irregular income. Residents can consult HAAM’s event listings for the full schedule and participating locations.