I have a 50% discount coupon for the Players' Handbook (I purchased the D&D Essentials Kit - boxed set) and I plan to use it.

Will I receive a discount on the Legendary / Sourcebook / other bundles if I were to purchase a bundle later?  This is because I would be purchasing the Player's Handbook if I bought a bundle later when I already own the handbook.  Will the value of the Player's Handbook be deducted from the price of the bundle?  How can I arrange for this?

Yes, this will be automatically factored into future purchases of any bundles. Anything else you purchase, whether it be full sourcebooks or adventures or piecemeal options will also be deducted.

Quote from Stinkybear >>

I have a 50% discount coupon for the Players' Handbook (I purchased the D&D Essentials Kit - boxed set) and I plan to use it.

Will I receive a discount on the Legendary / Sourcebook / other bundles if I were to purchase a bundle later?  This is because I would be purchasing the Player's Handbook if I bought a bundle later when I already own the handbook.  Will the value of the Player's Handbook be deducted from the price of the bundle?  How can I arrange for this?

 The way their credit system works is the amount you spend not the value of what you own is deduced.

Say the legendary bundle consists of 10 books that each cost $30 for a total value of $300, minus the 15% discount for a price of $255

1. You spend $30 on a $30 book in the bundle. The bundle will now cost you $225 ($30 credit)
2. You get a 15% off code for a book, meaning you spend $25.50 on the book. The bundle will now cost you $194.50 ($30 + $25.50 credit)
3. You buy the PHB with a 50% off code for $15. The bundle will now cost you $179.50 ($30 + $25.50 + $15 credit)
4. There are 7 books remaining and you get a 20% code. You decide to buy all the remaining books with that code as it's cheap; $30 x 7 = $210, -20% = $168

Even though you now own all the books, the legendary bundle will still cost you $11.50. This is because your credit towards the bundle is less than the cost of the bundle. What this $11.50 gets you is a 15% discount off all future books.

Hope this makes sense?

Yes it does. Thanks for the examples

I have a follow up question: I bought the PHB at full price. There's now a sale on the Players Bundle, at $50, that includes the PHB. Do I get a credit for the already owned PHB? 

Is so, when? It doesn't seem to be factoring in at checkout. 

Credits are usually already factored in the price you view. 

Only promotions where you apply codes is included at checkout. 

Ah, ok. Thst wasn't clear. I signed out and looked at the price to confirm and saw it was $70ish.

Thanks!

I purchased the Adventure bundle but already had some of the books. The amount I paid for those books wasn't deducted from my purchase.