Plan Changes

Plan Changes: Upgrades, Downgrades, and Plan Switches

Plan changes on Google Play Billing Library (PBL) 9.x always mint a new purchase token. You pick a replacement mode that controls two things: when the user gets access to the new plan, and how Google handles the money between the old and new agreement. This skill walks you through selecting the correct mode and wiring it into BillingFlowParams.

Phase 1: Scope the Change

Before touching code, answer four questions about the requested switch:

1. Direction: is this an upgrade (new plan costs more), a downgrade (new plan costs less), or a lateral switch (same price, different cadence)?
2. Billing period: are you moving between plans with the same billing period (monthly to monthly) or across periods (monthly to annual, recurring to prepaid)?
3. Promotional state: is the user currently inside a free trial or introductory price window that should survive the switch?
4. Additivity: is the new SKU replacing the old subscription, or should it sit alongside the old one as an add on?

Write those four answers down. Every decision in Phase 2 follows directly from them.

You also need two inputs from the client at runtime:

• oldPurchaseToken: the purchase token for the subscription the user is leaving.
• ProductDetails and offer token for the new plan, fetched through queryProductDetailsAsync.

If either is missing, stop and fetch it first. Launching the billing flow without a valid oldPurchaseToken produces a new standalone subscription rather than a plan change.

Phase 2: Plan the Replacement Mode

PBL 9.x exposes replacement modes through the ReplacementMode interface. UNKNOWN is deprecated; do not select it. The five modes you actually pick from are listed below, along with KEEP_EXISTING which arrived in PBL 8.1 for add on bundles.

Mode Decision Table

Use this table to map your Phase 1 answers to a mode.

Two rules keep you out of trouble:

• CHARGE_PRORATED_PRICE only works for upgrades. Using it on a downgrade makes the billing flow fail because Google does not refund through proration.
• CHARGE_FULL_PRICE is required for any switch that involves a prepaid plan, since prepaid plans have no recurring cycle to prorate.

Trade offs to Communicate in Your UI

Each mode has a user facing surprise you need to preempt:

• WITH_TIME_PRORATION shortens the next renewal interval on upgrades. Show the new renewal date.
• CHARGE_PRORATED_PRICE posts a small charge now. Show the amount before launching the flow.
• CHARGE_FULL_PRICE posts the full new price now. Do not hide this behind a generic confirmation.
• WITHOUT_PRORATION gives paid access until next renewal. Outside trials this is revenue you chose to give away.
• DEFERRED delays the switch. Tell the user "You will switch to Basic on " using the current line item's expiryTime.

The Play Console Default

You can configure a default replacement mode per subscription in Play Console under Monetize > Subscriptions. That default only applies when the client omits the mode from BillingFlowParams. Treat it as a safety net, not a substitute for setting the mode explicitly in code.

Phase 3: Wire Up SubscriptionProductReplacementParams

SubscriptionUpdateParams is the deprecated path. Starting with PBL 8.1, build SubscriptionProductReplacementParams and attach it to the product parameters instead.

Build the replacement params with the mode you picked in Phase 2. The example below implements a standard upgrade that keeps the billing date stable.

val replacement = BillingFlowParams
    .SubscriptionProductReplacementParams
    .newBuilder()
    .setOldPurchaseToken(currentPurchaseToken)
    .setReplacementMode(
        ReplacementMode.CHARGE_PRORATED_PRICE
    )
    .build()

Attach it to ProductDetailsParams for the new plan:

val productParams = BillingFlowParams
    .ProductDetailsParams.newBuilder()
    .setProductDetails(premiumDetails)
    .setOfferToken(premiumOfferToken)
    .setSubscriptionReplacementParams(replacement)
    .build()

Launch the flow:

val flowParams = BillingFlowParams.newBuilder()
    .setProductDetailsParams(listOf(productParams))
    .build()

billingClient.launchBillingFlow(activity, flowParams)

The structural change from the deprecated API is that replacement data rides with the product, not with the flow. That shape matches what you are saying: "I want this product, and it should replace this existing subscription."

Handling the Result

PurchasesUpdatedListener receives a new Purchase with a new purchase token. Send that token to your backend. Your server then calls purchases.subscriptionsv2.get and inspects linkedPurchaseToken:

fun handleNewPurchaseToken(newToken: String) {
    val subscription = playApi
        .getSubscriptionV2(packageName, newToken)
    val linked = subscription.linkedPurchaseToken
    if (linked != null) {
        database.markReplaced(linked)
    }
    database.insertSubscription(
        purchaseToken = newToken,
        productId = subscription.productId,
        status = "ACTIVE"
    )
}

Walk the chain if you may have missed prior notifications: the linked token might itself have been replaced by an even older token you still show as active.

Deferred Mode Specifics

With DEFERRED, the new token arrives immediately but carries two line items: the current plan (active, with an expiryTime) and the new plan (pending via deferredItemReplacement). Grant entitlement based on the active line item and schedule the switch for the expiry time:

for (item in subscription.lineItems) {
    if (item.deferredItemReplacement != null) {
        upcomingProductId = item.productId
    } else {
        currentProductId = item.productId
        switchAt = item.expiryTime
    }
}

When the renewal fires, Google sends an RTDN and you promote the pending plan to active.

Verification Checklist

Before shipping a plan change flow, confirm all of the following:

• You set oldPurchaseToken on SubscriptionProductReplacementParams using the token from the active subscription, not a stale cached value.
• The replacement mode matches the direction and promotional state from Phase 1.
• You do not pass CHARGE_PRORATED_PRICE for downgrades.
• Any switch involving a prepaid plan uses CHARGE_FULL_PRICE.
• Your backend reads linkedPurchaseToken and marks the old record replaced before activating the new one.
• For DEFERRED, your UI surfaces the scheduled switch date from the current line item's expiryTime.
• You acknowledge the new purchase on your backend after verification.

References

• Full chapter