AT&T Inc. (NYSE:T) stock is about to trade ex-dividend in 4 days time. If you purchase the stock on or after the 9th of January, you won't be eligible to receive this dividend, when it is paid on the 3rd of February.

AT&T's next dividend payment will be US$0.52 per share. Last year, in total, the company distributed US$2.04 to shareholders. Looking at the last 12 months of distributions, AT&T has a trailing yield of approximately 5.3% on its current stock price of $39.06. Dividends are a major contributor to investment returns for long term holders, but only if the dividend continues to be paid. So we need to check whether the dividend payments are covered, and if earnings are growing.

Check out our latest analysis for AT&T

Dividends are typically paid out of company income, so if a company pays out more than it earned, its dividend is usually at a higher risk of being cut. AT&T paid out 91% of its earnings, which is more than we're comfortable with, unless there are mitigating circumstances. Yet cash flow is typically more important than profit for assessing dividend sustainability, so we should always check if the company generated enough cash to afford its dividend. Over the last year it paid out 51% of its free cash flow as dividends, within the usual range for most companies.

It's good to see that while AT&T's dividends were not well covered by profits, at least they are affordable from a cash perspective. Still, if this were to happen repeatedly, we'd be concerned about whether the dividend is sustainable in a downturn.

Click here to see the company's payout ratio, plus analyst estimates of its future dividends.

Have Earnings And Dividends Been Growing?

When earnings decline, dividend companies become much harder to analyse and own safely. If business enters a downturn and the dividend is cut, the company could see its value fall precipitously. With that in mind, we're discomforted by AT&T's 8.2% per annum decline in earnings in the past five years. When earnings per share fall, the maximum amount of dividends that can be paid also falls.

The main way most investors will assess a company's dividend prospects is by checking the historical rate of dividend growth. AT&T has delivered an average of 2.4% per year annual increase in its dividend, based on the past ten years of dividend payments. That's intriguing, but the combination of growing dividends despite declining earnings can typically only be achieved by paying out a larger percentage of profits. AT&T is already paying out 91% of its profits, and with shrinking earnings we think it's unlikely that this dividend will grow quickly in the future.