From the replies I’m assuming you’re asking about manufacturers coupons . So , I’ve had no problems...as a matter of fact occasionally you can get products for “free” after rebates
Manufacturing coupons comes from different sources. 1) is sunday paper insert (can get paper from most stores including dollar tree). 2) online through sites like coupons.com, retailmenot, smartsource or direct from manufacture as internet coupons. 3) peelie which is a coupon that is directly on a product being purchased in store. There are other sources as well including loading digital manufacturing coupons onto a loyalty card/account (like walgreens). Coupon stacking depends on store coupon policy and restriction on coupon itself. Some stores allow loyalty coupon and manufacturing coupon to be used in same transactions. If physical coupons are used give to cashier for scanning. Then scan loyalty card or input number where possible to stack savings. Then scanning the receipt through ibotta should allow even more savings.