A giant depot in Doncaster will be worth £15m-a-year to the council in business rates - as a major government grant is cut to zero.
The iPort development will pay the sum when complete, expected to be from 2020.
The boost will come in the same year the revenue support grant from central government - worth £48m this year - is scrapped.
The figures were revealed on the day Mayor Ros Jones toured the site, which includes an enormous Amazon warehouse set to open later this year.
It alone will be worth £2.5m in business rates. The bill will be paid by the building’s owner, developer Verdion.
Mayor Jones said the business rates would “enhance and assist” as the RSG was axed.
It falls from £48m to £36m to £28m to £20m in 2020 and then zero.
The council has a gross revenue spend of £480m-a-year.
She added: “That’s why we need to grow our economy.” Current occupiers include Amazon, Fellowes, Ceva and Lidl.
Verdion also unveiled a new warehouse which is available for rent.
In a speech to property agents and potential occupiers, Mayor Jones said: “This is a major success for Doncaster, the growth has been astounding and shows we are open for business.”
John Clements of Verdion said they had been working on iPort for 15 years and until two years ago it was a muddy, waterlogged field.
Now, they had pressed the button on the southern phase, set to include 12 more buildings and a five-siding railhead capable of handling trains half-a-mile long.
He added: “It’s gone well here, Doncaster Council is very business friendly.” iPort, just off Junction 3 of the M18, is a £500m project for a rail freight interchange and logistics centre and is set to create 5,000 jobs.
Amazon has two warehouses on the site. A fulfilment centre is already open and a second is under construction, set to cost £100m and employ 1,500.