Proration

When a customer upgrades or downgrades their plan in the middle of a billing period, PayBridgeNP can automatically calculate the unused credit on their current plan and the cost of the new plan for the remaining time - then generate a proration invoice for the net difference.

How proration works

Proration is calendar-day based:

Credit = (remaining days / total days in period) × current plan amount
Debit = (remaining days / total days in period) × new plan amount
Net = debit − credit

A positive net means the customer owes more (upgrade). A negative net means a credit balance (downgrade) - no invoice is generated in that case.

Preview before applying

Always preview the proration amounts before committing a change so you can show the customer what they’ll owe:

const preview = await paybridgenp.subscriptions.previewProration(
  "sub_xxx",
  "plan_premium_monthly"
);

console.log(`Credit:  NPR ${preview.creditAmount / 100}`);
console.log(`Debit:   NPR ${preview.debitAmount / 100}`);
console.log(`Net due: NPR ${preview.netAmount / 100}`);

preview = paybridgenp.subscriptions.preview_proration("sub_xxx", "plan_premium_monthly")
print(f"Net due: NPR {preview['netAmount'] / 100}")

$preview = $pb->subscriptions->previewProration("sub_xxx", "plan_premium_monthly");
echo "Net due: NPR " . ($preview['netAmount'] / 100);

Apply a plan change with proration

Pass prorationBehavior: "create_prorations" to apply the change immediately:

const result = await paybridgenp.subscriptions.changePlan("sub_xxx", {
  newPlanId: "plan_premium_monthly",
  prorationBehavior: "create_prorations",
});

if ("proration_applied" in result && result.proration_applied) {
  const invoice = result.proration_invoice;
  console.log("Proration invoice:", invoice?.id, "Amount:", invoice?.amount_due);
}

result = paybridgenp.subscriptions.change_plan("sub_xxx", {
    "newPlanId": "plan_premium_monthly",
    "prorationBehavior": "create_prorations",
})

if result.get("prorationApplied"):
    invoice = result.get("prorationInvoice")
    print("Invoice:", invoice.get("id") if invoice else "No net charge")

$result = $pb->subscriptions->changePlan("sub_xxx", [
    "newPlanId"          => "plan_premium_monthly",
    "prorationBehavior"  => "create_prorations",
]);

if ($result['prorationApplied']) {
    echo "Invoice: " . ($result['prorationInvoice']['id'] ?? "no net charge");
}

Schedule for next billing cycle (default)

To keep the existing behavior - plan change applies at next renewal with no proration:

const result = await paybridgenp.subscriptions.changePlan("sub_xxx", {
  newPlanId: "plan_premium_monthly",
  // prorationBehavior defaults to "none"
});

Proration invoice

When a proration invoice is created it:

Has status: "open" if netAmount > 0 (customer owes money)
Is skipped (no invoice) if netAmount ≤ 0
Contains two line items: proration_credit (negative) and proration_debit (positive)
Is due immediately - link the customer to the hosted invoice page to collect payment

API reference

Endpoint	Description
`GET /v1/billing/subscriptions/:id/preview-proration?newPlanId=`	Preview amounts without committing
`POST /v1/billing/subscriptions/:id/change-plan`	Change plan; pass `prorationBehavior`

Getting Started

Accepting Payments

Checkout

Providers

Subscriptions & Billing

Branding

Operations

Integrations

How proration works

Preview before applying

Apply a plan change with proration

Schedule for next billing cycle (default)

Proration invoice

API reference

​How proration works

​Preview before applying

​Apply a plan change with proration

​Schedule for next billing cycle (default)

​Proration invoice

​API reference

How proration works

Preview before applying

Apply a plan change with proration

Schedule for next billing cycle (default)

Proration invoice

API reference