How long can dividends remain payable?

Many small business owners declare a dividend or bonus in order to pay themselves. At year-end, a company could declare a bonus of $20,000, payable within 180 days of the year-end. This would reduce operating income in the year even though the bonus would not be paid out until 6 months later. My question is, if a company declares a dividend at year-end and reports a 'dividend payable' liability on the balance sheet, is there a maximum time (like the 180 day-rule for bonuses payable) that the dividends payable can sit without being actually paid?