The Municipal Securities Rulemaking Board is seeking to require dealers go after best execution pricing for municipal bond orders by retail investors.

The requirement would take effect one year after it would be approved by the Securities and Exchange Commission.

Under the rule, dealers would be required to use “reasonable due diligence” to obtain the best buy or sell price under prevailing market conditions, the MSRB said in its request for authority from the SEC, which was published in the Federal Register on Monday.

The factors dealers must consider in determining the optimal price include the number of markets checked, size of the order and the market for the bond or similar municipal debt, and the accessibility of quotations.

Not having sufficient staff or good enough technology would not excuse a broker from the requirement.

Public comments are due to the SEC by September 29, but federal agencies routinely accept submissions after the formal date.