Stay, or sell and rent?

The math

• Each month, this year: your income, minus living costs, minus housing. Housing is property tax, insurance, repairs, and dues if you stay; rent and renters insurance if you rent.
• Savings you could reach: if you sell, the sale price minus agent and closing costs, the tax you entered, moving, and the deposit, plus the savings you have.
• Each year after: each cost grows at its own rate. Savings earn their rate on the balance at the start of the year, then the year's leftover money is added, or the shortfall taken out, at the end of the year. A one-time bill is paid at the start of its year.
• Repairs: your repair budget is treated as spent every year, not piled up in a separate fund. Money you don't spend is already part of your savings. A big repair uses up that year's replacement money first, so it isn't counted twice.
• When savings run out: the calculator stops counting them as savings and shows how short the money would be. It doesn't borrow against the house or assume you cut spending, though real people would.

What it leaves out

• Buying a smaller home, a reverse mortgage, or taking in a lodger.
• Long-term care, and how a spouse's death changes income and costs.
• Market ups and downs: the same return every year is a simplification.
• Income taxes on investment growth beyond the "after fees and taxes" rate you set.
• Utilities, transport, or other costs that differ between the two homes: add the difference to rent if you know it.

Taxes on the sale

The IRS lets you leave out of your income up to $250,000 of the profit on selling your main home, or $500,000 on a joint return. Profit is the selling price, minus selling expenses, minus your adjusted basis (roughly what you paid plus improvements). To qualify you generally must have owned the home and lived in it for at least 2 of the 5 years before the sale, and not used the exclusion on another home in the 2 years before. Some people who move early for work, health, or an unforeseeable event can get part of it. Profit above the limit may be taxable, and state rules can differ. Check your situation with IRS Publication 523 or a tax professional, then put your estimate in the box.