Joint bank account should be enough to show proof of "income" to live here
each agent( for the sponsorship) will probably want different things to process it
Here are the basics but again they vary agent by agent
Applicant is 55 years of age or older,
Possess a passport or travel documents with more than 18 months remaining validity,
Sbmit full identification (copy of all passport pages) and four passport photos 4 x 6 cm,
Curriculum vitae,
Statement from Pension Fund Foundation or Bank from the country of origin (or Indonesia) of funds available, minimum of US$1,500 per month, to provide the applicant living expenses during the proposed stay in Indonesia (Total US$18,000 per year) (VERY stiff compared to other countries requirements - US$600/month in Panama),
Proof of medical/health Insurance, life insurance, and third-party personal liability insurance in country of origin or Indonesia,
Statement of living accommodation in Indonesia. Minimum cost of US$35,000 if purchased house/apartment or, a minimum rental cost of US$500/month in Jakarta, Bandung, and Bali; US$300/month for other cities in Java Island, Batam, and Medan, and other cities a minimum US$ 200/month.) in the tourist areas according to the regulations,
Statement to declare employment of an Indonesian maid servant whilst living in Indonesia,
Payment of Immigration Fee based on effective regulations,
Sponsor letter from the appointed travel agency, costs to be paid by applicant,
Statement agreeing not to engage in business activities or work for a living. You MAY NOT WORK in Indonesia on this visa!
You may stay in Indonesia for one year on this visa, extendable for up to a maximum stay of five years.