Como dizer "abater o valor do que devo" em inglês

There's no need for you to pay me this amount. You can discount it on 200 reais that I owe you.

Não posso afirmar que a preposição que eu usei depois do verbo "discount" está certa. Esperemos, então, por outras opiniões.

There's no need to pay that amount. You can apply it to the $200 I owe you.

Complemento:

There's no need to pay me this amount. You can deduct it from the $ 200 I owe you.

''Speaking of which…you want to get something to eat? My treat. I'll deduct it from the seventy thousand dollars I owe you.'' [Google - Almost There And Back Again - Chapter 31]

Olá pessoal,

É possível usar '' There's no need to pay me this amount, you can discount it FROM the 200 reais I owe you'' ?

Valeus

This one is not the most natural way to say that, I am afraid. Looks like Portuguese in English to me.

Olá,

Mas a frase é praticamente a mesma igual a do Simon Vasconcelos o que mudei foi a preposição de ON para FROM qual seria a mais indicada?

Valeus

The catch isn´t on the preposition. In fact I wouldn´t use the "discount" word, in English whenever I saw it, it had a ring (a sense) of "paying less than you owe".
If negotiatint your debt with your credit agency, bank, financial institution etc, certainly you need a discount (say 10%, 15%, of the ammount you owe). There´s the cases of sale discounts in shops, on products etc.
https://blog.kissmetrics.com/downside-of-discounts/

So, I would stick to deduct it from...(a bit more formal I think) or "apply it to" (the amount you owe someone else...) [a bit more informal, to my thinking.)

Back then, I spent a lot of time on the phone with my lender. I’d pay a huge chunk of my loan, and instead of applying it to the principal, they’d apply it to future interest — and the interest amount was predetermined to be for a 20-year period.

http://www.getrichslowly.org/blog/2013/ ... in-a-year/

Taking it to an even more informal/colloquial way, you can use the "take it off" that was suggested by Telma.
Thanks guys for sharing your views.