Covered Calls: How to Earn Income on Stocks You Already Own

A covered call sells the right hand tail of your stock for cash today. You keep the shares, you keep the dividends, you keep every dollar of downside, and you hand over everything above the strike, and whether that is a good trade depends entirely on numbers you can compute before the order goes in. Here they are.

The trade, and the four numbers that define it

You own 100 shares bought at $100, a cost basis of $10,000. The stock sits at $100 today. You sell one call with a $105 strike, 42 days out. You collect $2.50 per share.

premium received = $2.50 x 100 = $250

breakeven = cost basis - premium = $100.00 - $2.50 = $97.50

max profit = (strike - basis + premium) x 100 = ($105 - $100 + $2.50) x 100 = $750

max loss = (basis - premium) x 100 = $9,750, if the stock goes to zero

The premium is yours the instant the order fills. No subsequent event can take it back. What you surrendered is every dollar the stock earns above $105. Six weeks of it.

Two return figures are worth computing. Brokerage marketing quotes whichever is larger.

static return = premium / cost basis = $2.50 / $100 = 2.5%

if called return = (strike - basis + premium) / basis = $7.50 / $100 = 7.5%

Both are returns over 42 days. Annualizing them ranks one strike against another. It promises nothing.

annualized static = 2.5% x 365 / 42 = 21.7%

annualized if called = 7.5% x 365 / 42 = 65.2%

That 65.2% assumes you repeat the identical trade nine times a year at the identical premium, with implied volatility obliging and the shares never leaving the account. I have never seen a year cooperate like that. Compare candidate strikes with the annualized numbers, then forget them.

The payoff, sitting next to the shares alone

At expiry the position is worth min(stock price, $105) x 100. Add the $250 premium. Subtract the $10,000 you paid.

Stock at expiry	Shares worth	Premium kept	Total P/L	Shares alone
$85.00	$8,500	$250	-$1,250	-$1,500
$90.00	$9,000	$250	-$750	-$1,000
$95.00	$9,500	$250	-$250	-$500
$97.50	$9,750	$250	$0	-$250
$100.00	$10,000	$250	+$250	$0
$105.00	$10,500	$250	+$750	+$500
$110.00	$10,500 called	$250	+$750	+$1,000
$120.00	$10,500 called	$250	+$750	+$2,000

The final column is the honest one. It goes missing from most covered call pitches. The strategy beats holding the shares in every row up to $107.50. Above that it loses. At $120 you earned $750 while the shares alone earned $2,000, so writing the call cost $1,250 in forgone gain on a trade your statement will record as a winner.

That is the structural bargain. You are paid $250 in advance for a claim on an amount that is unknown when you sell it and can be very large.

Every strike is a different trade

Same 42 day expiry, stock at $100. Delta doubles as a rough estimate of the model implied chance the contract finishes in the money, so it reads as approximate assignment odds.

Strike	Premium	Delta	Static return	If called return	Upside kept
$100	$4.10	0.53	4.1%	4.1%	None
$105	$2.50	0.35	2.5%	7.5%	$5.00
$110	$1.20	0.18	1.2%	11.2%	$10.00
$115	$0.55	0.09	0.6%	15.6%	$15.00

The at the money call pays the most cash and surrenders all of the upside on the day you sell it, which converts your stock position into a fixed income position with equity downside attached. The $115 call collects $55, and a commission plus two bid-ask spreads can reduce that to something close to a rounding error before the stock has done anything.

The middle of that table is where most of the reasonable trades live. The premium column exists only because of implied volatility. Writing calls when implied volatility is near the bottom of the stock’s own range means giving up the upside cheaply, which is why IV rank belongs in the decision. The method is in implied volatility explained. The delta figures come from the model described in the option Greeks.

Assignment, dividends, tax and the roll

American-style equity options can be exercised at any time before expiry. A short call carries early assignment risk from the moment it is sold. Two situations raise the odds materially. The call goes deep in the money and its remaining time value approaches zero, at which point the holder loses nothing by exercising. Or a dividend approaches, and the dividend exceeds the call’s remaining time value, which gives the holder a reason to take the shares before the ex-dividend date.

In P/L terms assignment is the good outcome, since it delivers the $750 maximum. What it changes is timing and tax. Shares sold inside a year attract short term rates. That problem is set out in tax-efficient investing. On a long held position with a large embedded gain, the tax bill from assignment can exceed several years of premium, and the strategy works far better inside a retirement account where that friction disappears. If the shares are held for the income, assignment before the ex-dividend date forfeits the payment, and the calendar mechanics are in dividend investing.

Rolling means buying back the short call and selling another. Usually further out in time, often at a higher strike. It is two trades. Price it as one net number. Suppose the stock has risen to $107 with a week left and your $105 call costs $2.60 to close, while next month’s $110 call sells for $2.20. The roll costs $2.60 - $2.20 = $0.40, so $40 net debit, and in exchange you lift the cap by $5, which is $500 of additional upside, and push expiry out a month. At that price it is a sensible trade.

Rolling a losing call down and out on a falling stock is a different animal wearing the same name, collecting more premium while tightening the ceiling on a position that already shows an unrealized loss, and it is usually chosen because closing the position would require admitting something.

Where covered calls fail

They fail on the stock that runs. That failure is systematically underweighted, because the position still shows a profit. They fail on the stock that falls, because $250 of premium does almost nothing against a $1,500 decline. The premium is a thin buffer and a hard ceiling. Only one of those two is discretionary.

They fail worst on positions you did not want in the first place. Writing calls against a holding to make a loss feel smaller keeps you in a declining stock for $250 a cycle, and the accounting gets steadily more creative as the shares fall. Decide whether you want to own the shares. Then decide whether to write against them.

There is also a capital constraint that catches newer sellers. One contract requires 100 shares, so a $100 stock means $10,000 committed before a single call can be written, and on a $40,000 account that is a quarter of the portfolio in one name. No amount of premium income offsets the concentration. Sizing comes before strike selection, using the framework in diversification explained.

Run across many cycles, covered call writing produces the stock’s return with the right tail removed and the left tail fully intact, plus whatever the premiums added back. In a market that grinds sideways that shape is attractive. In a market that trends hard upward it is expensive, and the cost arrives as a portfolio that rose less than the index it was built from while feeling productive every month.

Next: cash-secured puts, the same payoff approached from the other side and the usual entry into the wheel, and vertical spreads explained for defined risk versions of the same directional views. The options fundamentals quiz tests the assignment rules.