The Social Security Administration (SSA) will send you a letter (predetermination notice) if you have to pay an IRMAA based on your income. This letter explains why you need to pay more, the income reviewed, and how to appeal errors. A second letter (initial determination) provides your final premium amount and appeal rights if you disagree with the IRMAA determination.The Social Security Administration (SSA) will send you a letter (predetermination notice) if you have to pay an IRMAA based on your income. This letter explains why you need to pay more, the income reviewed, and how to appeal errors. A second letter (initial determination) provides your final premium amount and appeal rights if you disagree with the IRMAA determination.