The UK single chart rules have been changed to stop taking account of downloads given away in competitions, the BBC has announced.
The decision by the Chart Supervisory Committee, which governs the weekly list, comes into effect for today's chart.
The committee says the move ensures the chart reflects the bestselling singles.
In July, downloads given to fans of Sir Elton John who entered a prize draw to see the singer perform in Las Vegas helped his single reach the top five.
Sir Elton's single Electricity had been one of the cases to highlight the problem, said Omar Maskatiya, chart director of the Official UK Charts Company.
"The previous rules were too vague for either physical or digital singles but until recently the prizes on offer have been of very little value," he said.
"We acted to ensure the chart is a reflection of the best-selling singles rather than the best competitions.
"Competitions are still allowed around releases but not those dependent on the purchase of a single."
The committee is made up of representatives from record companies and retailers.