Regular readers will know that we love our dividends at Simply Wall St, which is why it's exciting to see StarHub Ltd (SGX:CC3) is about to trade ex-dividend in the next 4 days. The ex-dividend date is usually set to be one business day before the record date which is the cut-off date on which you must be present on the company's books as a shareholder in order to receive the dividend. The ex-dividend date is an important date to be aware of as any purchase of the stock made on or after this date might mean a late settlement that doesn't show on the record date. This means that investors who purchase StarHub's shares on or after the 29th of April will not receive the dividend, which will be paid on the 16th of May.

The company's next dividend payment will be S$0.042 per share, and in the last 12 months, the company paid a total of S$0.084 per share. Last year's total dividend payments show that StarHub has a trailing yield of 6.7% on the current share price of S$1.25. Dividends are an important source of income to many shareholders, but the health of the business is crucial to maintaining those dividends. That's why we should always check whether the dividend payments appear sustainable, and if the company is growing.

Check out our latest analysis for StarHub

If a company pays out more in dividends than it earned, then the dividend might become unsustainable - hardly an ideal situation. It paid out 82% of its earnings as dividends last year, which is not unreasonable, but limits reinvestment in the business and leaves the dividend vulnerable to a business downturn. It could become a concern if earnings started to decline. That said, even highly profitable companies sometimes might not generate enough cash to pay the dividend, which is why we should always check if the dividend is covered by cash flow. Over the last year it paid out 51% of its free cash flow as dividends, within the usual range for most companies.

It's positive to see that StarHub's dividend is covered by both profits and cash flow, since this is generally a sign that the dividend is sustainable, and a lower payout ratio usually suggests a greater margin of safety before the dividend gets cut.

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

Have Earnings And Dividends Been Growing?

Companies with falling earnings are riskier for dividend shareholders. 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 StarHub's 5.9% per annum decline in earnings in the past five years. Ultimately, when earnings per share decline, the size of the pie from which dividends can be paid, shrinks.