The body of James Huggett, 71, was found when officers called to investigate why he owed more than £1,000 in rent to Lambeth LBC.
But neither the area housing department, who visited his home twice, or social services had previously considered alerting police, Southwark Coroners Court was told.
Coroner Sir Montague Levine said: 'In the early stages Mr Huggett may have been ill and couldn't get to the door; later he would have died.
The discovery of Mr Huggett's badly decomposed body was made by housing officer Jacqueline Simms on 18 August this year.
She said Mr Huggett, who had always paid his rent on time, owed £1,031. Ms Simms had visited the flat with a view to eviction because of the unprecedented arrears.
Ms Simms said she had called twice at the flat earlier in the year and also contacted social services about the arrears. But she admitted she had not alerted police.On 18 August with the help of a fellow council worker she forced open the door.
The coroner asked if there was a directive on what should be done in such cases.
Ms Simms said there was such a directive but did not elaborate. She told the court she had contacted social services in April but they had no record of Mr Huggett.