USD 100 repaid in March, USD 100 repaid in April and USD 100 repaid in May.

[kachibibibi]

Say I am writing a legal document and a person has to repay a total of USD 300 to another person in 3 months, so each month he repays USD 100.

Person A repaid USD 100 to Person B in March, another USD 100 in April and the last USD 100 in May.

I know it is not a natural way to put it. How would native speakers write?

I think of these two:

Person A repaid USD 300 to Person B in 3 months, with USD 100 for each month.
Person A repaid USD 300 to Person B in 3 months in monthly installments.

But I am not sure if they work, in particular, does "installment" necessarily mean "an equal amount"?

 

[Tarheel]

XX paid YY $300 in monthly installments of $100 each.

 

[5jj]

Person A is to repay the $300 in three monthly instalments of $100 each, beginning on 18 March 2024.