The latest round of ABCs showed the magazine is holding on as the number two TV listings magazine, but is in danger of slipping behind its rivals.
The BBC Worldwide magazine saw circulation fall 4.2% last year, although was it up 0.4% in the last six months, to 1,108,718 copies, behind market leader IPC Media's What's on TV, which recorded sales of 1,587,578.
Radio Times third-place rival Bauer's TV Choice, which has a circulation of 1,104,291 copies, was up 8.5% last year.
Radio Times is investing a further £1m in sales promotion and direct marketing campaign, which will target 250,000 readers.
The latest campaign follows a similar push last year, which was commended in the DMA People's Choice awards.
Readers are being offered the chance to win up to £100,000 to pay off their mortgage in the promotion, which will begin on March 15 and runs for a month.
The magazine will be printing 12 questions over the four weeks, giving readers multiple opportunities to enter the promotion.
The sales promotion will be supported above-the-line nationally on Virgin Radio as well as selected local radio stations. The ad will be voiced by comedienne and novelist Arabella Weir and will air in the morning and evening drive-time slots.
Kathy Day, publisher of Radio Times, said: "Last year saw an extensive research and development programme on Radio Times, culminating in editorial changes that reinforce its position as the intelligent television listings magazine."
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