Every credit card ad tells you the earning rate. Almost none of them mention when that rate stops. The Amex Gold earns 4x on groceries — until it doesn't. The Chase Freedom Flex earns 5x on rotating categories — until it doesn't. The Citi Custom Cash earns 5% on your top category — until it doesn't.
These earning caps are the single most important detail that gets buried in the fine print, and for higher spenders and families, they can completely change which card is actually the best choice.
What Is an Earning Cap?
An earning cap sets a maximum dollar amount of spending that qualifies for a card's bonus rate in a given period (usually per calendar year or per quarter). Once you exceed that cap, your earning rate drops — typically to 1x or 1%. The base rate still applies, you just lose the bonus multiplier.
This means the earning rate you see advertised is a maximum, not a guarantee. Your actual effective rate depends on how much of your spending falls above vs. below the cap.
The Major Earning Caps You Need to Know
| Card | Bonus Rate | Category | Cap | After Cap | Period |
|---|---|---|---|---|---|
| Amex Gold | 4x MR | U.S. Supermarkets | $25,000 | 1x | Calendar Year |
| Amex Gold | 4x MR | Restaurants | $50,000 | 1x | Calendar Year |
| Amex Blue Business Plus | 2x MR | All Purchases | $50,000 | 1x | Calendar Year |
| Chase Freedom Flex | 5x UR | Rotating Categories | $1,500 | 1x | Per Quarter |
| Citi Custom Cash | 5% / 5x TYP | Top Category | $500 | 1% | Per Billing Cycle |
| Blue Cash Preferred | 6% Cash | U.S. Supermarkets | $6,000 | 1% | Calendar Year |
| US Bank Cash Plus | 5% Cash | 2 Chosen Categories | $2,000 | 1% | Per Quarter |
The Effective Rate Formula
When you spend above a cap, your actual earning rate is a weighted average of the bonus rate (on the capped amount) and the fallback rate (on everything above the cap). The formula:
Effective Rate = (Bonus Rate x Cap Amount + Fallback Rate x Overspend) / Total Spend
This is straightforward math, but it's the kind of math almost nobody does before choosing a card. Let's run it on the cards that matter most.
Amex Gold: The $25,000 Grocery Cap
The Amex Gold earns 4x MR at U.S. supermarkets up to $25,000/year, then 1x. Here's how the effective rate changes as grocery spending increases:
| Annual Grocery Spend | Bonus Earnings (4x) | Overage Earnings (1x) | Total Points | Effective Rate |
|---|---|---|---|---|
| $12,000 | 48,000 | 0 | 48,000 | 4.0x |
| $18,000 | 72,000 | 0 | 72,000 | 4.0x |
| $25,000 | 100,000 | 0 | 100,000 | 4.0x |
| $30,000 | 100,000 | 5,000 | 105,000 | 3.5x |
| $36,000 | 100,000 | 11,000 | 111,000 | 3.08x |
At $30,000/year in groceries ($2,500/month), you're only getting 3.5x effective. That's still excellent — but it's not the 4x that attracted you to the card. At $36,000/year, you're down to 3.08x. The higher your spend goes past the cap, the more that rate erodes toward 1x.
For most individuals spending $500–$1,500/month on groceries, the cap is irrelevant. For a family of five spending $2,500+/month at the supermarket? It matters. You might want to split grocery spend between two cards once you're approaching $25K.
Citi Custom Cash: The $500/Month Cap
The Citi Custom Cash earns 5% (or 5x ThankYou Points with a Strata Premier) on your highest eligible spending category each billing cycle, capped at $500 per month. That works out to $6,000/year.
This card is essentially a $500/month machine. If you can keep your spending in the target category at or below $500, you get the full 5%. But the moment you exceed it, the overage earns just 1%.
| Monthly Category Spend | Bonus Earnings (5%) | Overage (1%) | Total Cash Back | Effective Rate |
|---|---|---|---|---|
| $400 | $20.00 | $0 | $20.00 | 5.00% |
| $500 | $25.00 | $0 | $25.00 | 5.00% |
| $750 | $25.00 | $2.50 | $27.50 | 3.67% |
| $1,000 | $25.00 | $5.00 | $30.00 | 3.00% |
At $1,000/month, the effective rate is 3.00% — still decent, but you could get that from a no-cap card like the Capital One Savor (3% on dining/groceries/entertainment) without worrying about thresholds. The Custom Cash is brilliant when you stay inside it, but it punishes overspend quickly.
Chase Freedom Flex: $1,500/Quarter
The Freedom Flex earns 5x UR on rotating categories up to $1,500 per quarter ($6,000/year max bonus). You must activate each quarter's categories manually — forget to activate, and you earn 1x even on qualifying purchases.
The quarterly cap means you can earn a maximum of 7,500 bonus UR per quarter (1,500 x 5x), or 30,000 UR per year if you max every quarter. At 2.0 cents per UR (with a Sapphire card), that's $600/year in bonus value. Not life-changing, but it's from a no-annual-fee card.
The real issue with the Freedom Flex isn't the cap — $1,500/quarter is enough for most people in a single category. The issue is that the categories change, and groceries or gas might only show up one or two quarters per year.
Blue Cash Preferred: $6,000/Year on Groceries
The Blue Cash Preferred earns 6% cash back at U.S. supermarkets up to $6,000/year, then 1%. Six percent is the highest grocery cash-back rate available, but $6,000 is only $500/month. For a single person buying groceries for one, that might work. For a family, you'll blow through $6K by summer.
At $12,000/year in groceries: (6% x $6,000 + 1% x $6,000) / $12,000 = ($360 + $60) / $12,000 = 3.5% effective. At that level, you're getting worse value than the Amex Gold at 4x (worth ~8% at 2.0 CPP) with a much higher cap.
Why Families Get Hit Hardest
Caps are set at levels that work for individual spenders. A single person spending $400/month on groceries will never touch the Amex Gold's $25K cap or the Blue Cash Preferred's $6K cap. But combine two adults and two kids, and grocery spending easily hits $1,500–$2,500/month. That's $18K–$30K/year, which blows through the BCP's cap by February and starts eroding the Amex Gold's rate in the fall.
The fix for families: split spend across cards strategically. Use the high-bonus card until you approach the cap, then switch to your next-best option. Or add a second Citi Custom Cash (yes, you can have multiples) and alternate months.
Cards with No Earning Caps
Some cards worth noting have no caps at all:
- Chase Freedom Unlimited — 1.5x UR on everything, no cap
- Capital One Venture X — 2x miles on everything, no cap
- Citi Double Cash — 2% cash back on everything, no cap
- Chase Sapphire Reserve — 3x UR on dining and travel, no cap
- Chase Sapphire Preferred — 3x UR on dining, no cap
- Amex Platinum — 5x MR on flights booked direct, no cap
If you're a high spender who doesn't want to track thresholds, building your setup around uncapped cards gives you predictability. You'll sacrifice some peak earning rates, but you'll never have to worry about your rate quietly dropping mid-year.
The takeaway: always check the cap before you get excited about a multiplier. A card earning 5x on $500/month and a card earning 2x on everything are earning the same points at $1,250/month in that category. The math doesn't lie, even when the marketing does.