The phrase "a flat payment of" is correct and usable in written English.
It can be used when specifying a fixed amount of money that will be paid, regardless of any variables or conditions.
Example: "The contractor will receive a flat payment of $5,000 for the project, regardless of the hours worked."
Alternatives: "a fixed payment of" or "a set fee of".
But the criticism was so harsh that the group changed its policy and began offering a flat payment of $200.
Under the NEF proposal, the tax-free personal allowance would be scrapped and the proceeds used to fund a flat payment of £48.08 a week for every adult.
Those who were warned of the change in the cap – customers facing redemption charges – will receive a flat payment of £250, while the others will receive payments based on the difference in repayments caused by the change in the rate.
The defense would obviously be that the material was in the public domain, and the suit looked like the usual nuisance-value suit that Hollywood is plagued by — especially since Lundberg offered to settle for a flat payment of $18,000.
Describing the scheme as "shoddy, unfair and unjust", she said a flat payment of £500 for people denied access to higher education was "pitiful" when research showed the value of higher education over a lifetime amounts to tens of thousands of pounds.
Finally, in order to motivate subjects for careful consideration of the questions, 12 subjects drawn randomly received a flat payment of 20 Euros in the main test.
A 60-year agreement signed in 1933 established a flat payment to Iran of four British pounds for every ton of crude oil exported and denied Iran any right to control oil exports.
ASCL advocates establishing a national funding formula across the country, with a flat payment for all pupils regardless of where they live.
Mr. Reagan was asked about reports that elderly people were being discharged prematurely from hospitals because of a new Medicare payment system under which hospitals receive a flat payment for each case, depending on the patient's diagnosis.
Under this mixed-system, the retirement benefit of the PAYG-DB pillar was conformed of three parts, a flat payment, a benefit based on contributions made before the reform, and another based on contributions made after the reform.
