A widow who waits until her full retirement age of 66 (for those born between 1945 and 1956) can claim the full survivor benefit, which is 100 percent of her husband’s benefit. She is eligible for a survivor benefit at 60, but it will be reduced for each month she claims before 66. If both spouses are at least 70 when the husband dies, a wife should switch to a survivor benefit if her benefit is smaller than his.

Younger spouses have more options to maximize benefits, Mr. Levine said. For example, a surviving spouse who is the lower earner can create an income stream by collecting her own retirement benefit when she is eligible at 62 and switch to the higher survivor benefit when she turns 66. Taking her retirement benefit early will not reduce the survivor benefit.

A wife who is eligible for a higher retirement benefit should take the opposite tack: She can collect a reduced survivor benefit early and switch at 70 to her own retirement benefit.

Meanwhile, a spouse who inherits an individual retirement account has several choices. If she is younger than 70½ and does not need the money, she could, with the help of a brokerage firm, transfer her husband’s account directly into her own I.R.A. and then update the beneficiaries. She will not be required to take annual distributions until she is 70½, thus extending the time the funds can grow tax free.

If a widow is younger than 59½ and may need the money, she can transfer the assets into a new inherited I.R.A. She can take taxable distributions without having to pay the 10 percent penalty imposed on early withdrawers, Mr. Levine said.

Making Financial Decisions

For a preliminary assessment of cash flow, a widow can tote up sources of income and fixed expenses. But for a deeper dive, Ms. Alpert recommends adding a financial adviser to a team of professionals. While she and her husband already had an estate lawyer and an accountant, a friend helped her find a financial services firm. When she met with two young men from the firm, “I told them, ‘Take care of me like you would take care of your mother,’” she said.

The financial adviser may reposition investments to provide additional income, Ms. Armstrong said. Though each case is different, she said, “I believe in buying good-quality stocks where there is a good potential for rising dividends.” If Ms. Armstrong decides an annuity is a nice fit, she will analyze the oft-hidden costs of an array of complex products.