The optimal claiming age depends on health, other income sources, tax situation, and marital status. Claiming at 62 permanently reduces the monthly benefit by up to 30%. Waiting until 70 increases it by 8% per year beyond full retirement age. For couples, the interaction between both spouses' claiming decisions affects lifetime household income and is worth modeling carefully alongside the full income picture.

A Roth conversion moves money from a pre-tax IRA or 401(k) into a Roth account. The converted amount is treated as ordinary income in the year of conversion, and all future growth is tax-free. Whether and how much to convert in a given year depends on current versus expected future tax rates, IRMAA thresholds, and the size of pre-tax balances that will eventually be subject to required minimum distributions.

The 4% rule suggests withdrawing 4% of a portfolio annually to reduce the probability of depleting assets over a 30-year retirement. It is a useful reference point, but it does not account for taxes, Social Security timing, account type, or spending flexibility. Withdrawal strategies that incorporate these variables typically produce different results than a fixed percentage applied uniformly each year.

Required minimum distributions begin at age 73 under current law. They are calculated as a percentage of pre-tax retirement account balances and added to taxable income each year. This affects Social Security taxation, Medicare premium calculations, and the size of the taxable estate. For individuals with large pre-tax balances, the resulting annual distribution is often larger than anticipated if pre-tax balances were not reduced in earlier years.

An AUM-based fee is calculated as a percentage of assets under management, typically 0.75% to 1.25% annually. A flat fee is a fixed amount agreed upon in advance, independent of portfolio size. The practical difference is that a flat fee does not increase as assets grow, and it does not create a financial relationship between the advisor's compensation and the composition or size of the portfolio being managed.

Coordination means that individual retirement decisions — Social Security timing, withdrawal sequencing, Roth conversions, account selection — are evaluated together rather than independently. Each decision affects taxable income, which affects Social Security taxation, Medicare premiums, and after-tax investment returns. A plan that models these interactions produces different results than one that addresses each area in sequence as a separate problem.