دفع مع مرور الأشهر و السنوات

برنامج الدفع الفوري
ELIAS-HARRAP
BUSINESS DICTIONARY, ENGLISH/ARABIC
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Pay As You Go

Payments for a good or service as it is used rather than as an outright purchase. For example, college tuition is on a pay-as-you-go basis to obtain the courses necessary for completing college degree requirements.

ٌRef:Dictionary of Business Terms, 3rd edition, by Jack P. Friedman, published by Barron's Educational Series, Inc.
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pay as you go

Pay for purchases immediately instead of deferring payment. For example, Ruth and Bob had no credit cards; they believed in paying as you go. [First half of 1800s]
Idioms

Ref:The American Heritage Dictionary of Idioms, by Christine Ammer,
published by Houghton Mifflin Company

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I think may this idiom differ according the context.So, may any of the other answers fits your context more than my answer.

This is the most precise translation since pay as you go is described as:

Payments for a good or service as it is used rather than as an outright purchase. For example, college tuition is on a pay-as-you-go basis to obtain the courses necessary for completing college degree requirements.

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Note added at 10 hrs (2007-02-07 19:01:33 GMT)
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here is an example from a website

أيضاً بالنسبة للاشتراك بطريقة الدفع بحسب الاستخدام Pay as you go فقط تم تخفيض أجور ساعات الاستخدام حيث انخفضت قيمة الساعة من 42 ل.س إلى 36 ل.س.

here is the web address:
http://72.14.253.104/search?q=cache:EwLk57_8IQkJ:www.thisiss...

Hi,
I have two pay-as-you-go contracts. They do not require me to pay for anything unless I need to use it there and then. If you wanna use an hour, you pay for an hour, you wanna leave your account blank, you can.. no obligations. I belive they mean the same.
Hope this helps. Good luck.

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Note added at 30 days (2007-03-10 00:31:46 GMT)
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I should add however that if the text is criticizing the social security system it might mean:
برنامج لايلتجئون له الا في وقت الشدة
Because indeed I never pay for my contracts unless I am really at the end of my tether...

I dunno if the text is creating a new program for social security, or is criticizing social security. Hence, medium confidence.

The concept of pay-as-you-go means you do not have to pay for a service until you need to use it. So, when you go to use a service you pay for it, hence "pay-as-you-go