日本は経済停滞や円安の影響もあって生活コストは低いけれども、相続税が半端なく高いとのこと。例えば、国税庁によると、相続額が6億円を超えると限界税率が55%で、控除額はたったの7200万円（基礎控除を含めると1億円強になるが）。しかも、住民票を抜いて非居住者になったとしても、10年間は相続税の納税義務があるとのこと。

これを知って老後の計画が根本的に変わってしまった。ラーメン一杯3000円するような物価の高いアメリカに住んでいると自分は決して富裕層には感じないけれど、日本だったら相続税の心配をするぐらいの資産は持っている。日本は温泉とか食べ物が好きだし、医療サービスの質が高いので、長期的に住みたいと思ったけど、住民票を入れた瞬間に国税庁に追い回されるのはたまったものではない。アメリカの税制だと、夫婦の場合2800万ドル、今の為替レートで45億円ぐらいまでは遺産税が非課税だから、アメリカに居住するかぎり相続税のことは心配しなくていい。今後一生、たぶん日本に住民票を入れることはないだろうなと思った。

Geminiが言うには、老後は州税の低い（またはゼロ）のアメリカの州を生活の拠点にしつつ、日本の居住者とみなされない範囲内で数ヶ月単位で旅行するのが最適だそうだ。昔読んだ小説「永遠の旅行者」を思い出す。

During the 0% APR period, I racked up nearly $30,000 of credit card debt. By doing so, my credit score went down from around 835 to 795. However, I paid off the debt last week before the end of the 0% APR period. A few days later, my credit score went back to 835. Now that the 0% APR period is over and the credit card offers only 1.5% cash back on everything (less than 2% with my Fidelity card), I contacted Capital One to switch from Quicksilver to Savor, which offers 3% cash back on dining and bakeries.

I highly recommend the card to anybody. If you open an account by clicking this link, you will receive an extra sign-up bonus.

It is easy to explain why airport lounges are crowded. The cause is the failure to apply the price mechanism. Any competent student of economics knows that prices are determined to equilibrate supply and demand. When you set the price above the equilibrium price, supply will exceed demand. That is why the minimum wage policy causes unemployment. When you set the price below the equilibrium price, demand will exceed supply. That is why rent control causes a housing shortage.

It is the same with airport lounges. The usual way to access airport lounges is to have a credit card that grants access. For instance, holders of the American Express Platinum card can enter Centurion lounges. Now, holding the credit card incurs an annual fee, a fixed cost. But once you have the right credit card, you can access the lounge for free, so the marginal cost is zero. Demand responds to marginal cost, not fixed (sunk) cost. That is why demand for airport lounges exceeds supply (space).

I often fly through the Atlanta airport, and when I have enough time, I mindlessly visit the Centurion lounge at Terminal E. These days, it is not uncommon to wait 30 minutes, so I usually use the American Express app to get on the waitlist while I am still on the plane train to reduce the wait time. The other day, I saw a customer at the entrance furiously shout, “If we need to wait that much, it’s not worth it anymore,” and left. If American Express decides to charge a small entry fee to the lounge, like $5 or $10, I bet the crowds will quickly disappear. But paying a small entry fee each time is not exactly luxurious. An alternative is to sell lounge memberships separately or limit access to this number of times per year, as Delta Airlines does with its Sky Club lounges.

For comparison, I show the scatter plots from both 2023 and 2024. Congratulations to Jeff Clemens and Paul Niehaus for their substantial raises, as was the case in 2023. Notably, two faculty members in the lower left—Kaspar Wuthrich and I—have left. (Kaspar moved to Michigan, another public university, so curious readers can compare his salary before and after the move.) If I were the department chair, I would focus on retaining faculty in the lower left.

Contribute to IRA using backdoor Roth

In 2026, the IRA contribution limit increased to $7,500 (from $7,000). I will max out both for my wife and me.

Contribute to HSA

In 2026, the HSA contribution limit (family) has increased to $8,750 (from $8,550). Since I have two HSAs (one for my workplace and one with Fidelity), I will wait to contribute the last few hundred dollars to Fidelity to avoid over-contributing (since my workplace HSA sometimes offers additional benefits).

Donate stocks with capital gains to my kids’ UTMA accounts

Donating stocks lets me realize up to $1,350 in capital gains tax-free by using this loophole:

• The annual gift tax exclusion limit is $19,000 ($38,000 for married couples filing jointly) (see here).
• Child’s unearned income above $2,700 is taxed at parent’s rate (see here).
• Standard deduction for a dependent is $1,350 (see here).

Therefore, if the market value of the stocks I donate is less than $38,000 and capital gains are less than $1,350, the child does not need to pay any tax.

Use 529 funds wisely

Since July 2025, the K-12 qualified expenses for 529 plans have significantly expanded (see here). I will keep track of my expenses in a spreadsheet.

Pay off credit card debt

In 2025, my wife and I have racked up around $50,000 in credit card debt. This may sound insane, but actually, it was on purpose. We each opened the Capital One Quicksilver card, which offers 0% APR for 15 months and 1.5% cashback on all purchases. We used this card to pay taxes and purchase stuff for our bathroom remodeling project. I have been saving cash using Treasury bills (to avoid state income taxes), so we saved over a thousand dollars from the interest rate arbitrage. (However, my credit score declined from 840 to 790 by racking up credit card debt, though I don’t regret it.)

Downgrade American Express Blue Cash Preferred card

In this post, I mentioned that the AAA Daily Advantage Visa Signature card dominates the American Express Blue Cash Preferred card for groceries. I will downgrade the Amex card to one without an annual fee before the renewal date so that I can keep the long credit history (since 2010).

Use credit cards optimally

I will use my credit cards optimally.

• American Express Platinum Card for flight tickets booked directly with airline or through American Express Travel (5%) and prepaid hotels booked through American Express Travel (5%).
• American Express Blue Cash Preferred Card for groceries (6%) and transit (train, bus, parking, rideshare, etc.; 3%).
• Costco Anywhere Visa Card for Costco gas (5%), other gas and EV charging (4%), and dining (3%).
• AAA Daily Advantage Visa Signature Card for Costco (3%) and pharmacies (3%), and if I cancel the American Express Blue Cash Preferred card, then groceries (5%).
• Capital One Quicksilver Card for hotels, vacation rentals and rental cars booked through Capital One Travel (5%).
• Fidelity Rewards Visa Signature Card for any purcahse (2%).

Grocery shopping is one of them for me. Since 2010, I have been using the American Express Blue Cash Preferred card, which I recently discussed in this post. Just to recap, the annual fee is $95, and the cashback rate on groceries is 6% up to $6,000 in purchases, after which it drops to 1%.

I asked Gemini for some good grocery shopping cards. Not surprisingly, the Amex Blue Cash Preferred card came on top, but there were a few others. One of them, the AAA Daily Advantage Visa Signature card, drew my attention. There is no annual fee, and the cashback rate on groceries is 5% up to $10,000 spent.

The AAA Daily Advantage card’s rewards surpass those of the Amex Blue Cash card (net of annual fee), as shown below. Let \(x\) represent grocery expenditure. Ignoring the accelerated earnings cap ($6,000 for Amex, $10,000 for AAA), the break-even point satisfies: \[\frac{6}{100}x-95=\frac{5}{100}x\iff x=9500.\] Since the break-even point is above the cap for Amex ($6,000) and the cashback rate of AAA weakly dominates Amex beyond $6,000, it follows that AAA always dominates Amex.

Does this mean I should ditch the Amex card? Not so fast. If we look at the benefit structure of the AAA card, there is also a 3% cashback on wholesale club spending, including Costco, but the accelerated cashback rate applies only to the first $10,000 spent. Recalling that the cashback rate on the Costco Anywhere Visa card is 2% (see here), and that my annual household expenditure on Costco is about $10,000, it is better to reserve the AAA card for Costco instead of other grocery spending. Of course, if my wife also opens an AAA card, then we can just use two AAA cards to cover our entire Costco and grocery spending without hitting the combined $20,000 cap. I will first experiment with the AAA card (which I applied for just yesterday) and see how it goes.

The annual fee of the Delta Platinum card is $350. The rewards are:

• 3 miles per dollar for direct Delta and hotel purchases,
• 2 miles per dollar for dining,
• 1 mile per dollar for other purchases.

The value of a Delta SkyMile is just above 1 cent. The cashback rates of my other cards are:

• 5% for flight tickets and prepaid hotels with the American Express Platinum Card,
• 3% for dining with the Costco Anywhere Visa Card, and
• 2% for all purchases with the Fidelity Rewards Visa Signature Card.

Therefore, the rewards of the Delta Platinum card are dominated by my other cards.

Then why do I hold the Delta Platinum card? The reason is other tangible and intangible benefits:

• 2,500 Medallion Qualification Dollars (MQD) headstart
• Zone 5 priority boarding
• First checked bag free
• $120 rideshare credit ($10 per month)
• $120 Resy credit ($10 per month)
• $150 hotel credit booked through the Delta website
• 15% discount in miles when booking Delta award tickets
• Annual Companion Certificate

and so on. Among these benefits, the one I care about most is the 2,500 MQD headstart. In 2025, I qualified for Gold status thanks to this benefit. With Gold status, I get Zone 4 priority boarding, a high probability of seat upgrade, and lounge access when traveling internationally, etc. (Among these benefits, I only care about the upgrade, as my American Express Platinum card gives me lounge access pretty much everywhere.) The value of benefits other than the 2,500 MQD headstart is mixed. The $150 hotel credit is easy to use. The $10-per-month rideshare credit can only be used for rideshare, not Uber Eats, so it is difficult to use during the off-season. I often let the $10-per-month Resy credit expire because the amount is too small relative to the opportunity cost of searching for and visiting a Resy restaurant. I haven’t used the Annual Companion Certificate yet, so we will see whether it is valuable.

Overall, I am not that excited about this card, and I rarely use it, but I will likely keep it as long as I fly Delta often.

Optimizing this card is far from simple, which explains my love-hate relationship. To begin, the annual fee is $895, which is quite expensive. The awards structure is simple, however:

• 5 points per dollar spent directly on airlines or booking flights or hotels through American Express Travel.
• 1 point per dollar spent on everything else.

What makes this card complicated is that there are many benefits, some of which apply annually, semiannually, quarterly, or monthly, and at any time, there are 100 targeted offers. Navigating through these benefits (until I remember them) is mentally taxing.

This year, I recovered the following benefits.

• $200 for Uber. This is easy to remember because we get $15 Uber cash every month (with $20 extra in December). Because I can’t get reimbursed for Uber Cash as business expenses, I use it for personal Uber rides if there are any, and if not, I order random things on Uber Eats (and choose pickup to save on delivery fees).
• $200 for Resy. This is also easy to remember because we get $100 every quarter. I try to use it for business meals because we can get reimbursed.
• $148.27 for Lululemon. There is a $75 credit each quarter, and I ask my wife to purchase things that we would buy anyway.
• $100 for Saks Fifth Avenue. There is a $50 credit every half year, and I ask my wife to purchase things that we would buy anyway.
• $209 for Clear.
• $225 for Fine Hotels & Resorts or Hotel Collection. There is a $300 credit every half year, but it is difficult to use this credit because these hotels are expensive and some require a two-night stay. Ideally, I want to use this for a business trip that I can get reimbursed for, but this year, we used it for a family trip to Las Vegas.
• $142.83 in airline fee credit. You get $200 in incidental expenses for one airline of your choice. I chose Delta because I fly often, and I’ve used it for an upgrade to premium economy and for booking fees on award tickets and in-flight purchases.
• $213.1 by clipping coupons. Once I got $100 off for booking Delta, and another time $70 off for purchasing the Dropbox annual plan (both of which I would buy anyway).
• $8 for digital subscriptions. I signed up for the Wall Street Journal, which costs $1 per week at the moment.
• Finally, I earned 47,371 points for total spending (most of which is travel, obviously). I used these points for booking flight tickets, which I value at $473.71. (More on this here.)

Noting that the annual fee was $695 (before the increase), we can compute that the average cashback rate was 7.92%, which is pretty good. Every credit card needs to have a purpose to hold. For me, the reason for keeping the Platinum card is not the cashback rate but intangible benefits like access to Centurion Lounges and gold status at Hilton and Marriott. I wish American Express would reduce the annual fee by simplifying various benefits. (To me, Oura ring or digital subscriptions have no value.) I guess I will keep the card for now because I often fly through Atlanta, which has a Centurion Lounge, but if Capital One Venture X or Chase Sapphire Reserve expands their airport lounge networks, I might switch.

The structure is relatively simple. There is no annual fee, but only Costco members can have this card. (The Costco membership fee is $65 for Gold Star, which gives no benefits, and $130 for Executive, which gives 2% cashback. Therefore, conditional on being a Costco member, if one expects to spend more than \(65/0.02=3250\) dollars per year, the Executive membership is better. In what follows, we ignore the membership fee because it is independent of the credit card.) The rewards are

• 5% on gas at Costco,
• 4% on other eligible gas and EV charging,
• 3% on restaurants and eligible travel,
• 2% on Costco purchases, and
• 1% on all other purchases.

In the past, I have blindly used this card for gas (regardless of whether it was at Costco), EV charging, restaurants, Costco, and some travel. This year, I earned the following cashback:

• $1.05 on gas at Costco,
• $8.13 on other eligible gas and EV charging,
• $147.92 on restaurants,
• $172.52 on travel,
• $204.23 on Costco purchases, and
• $6.52 on all other purchases.

Based on this information, we can compute that the average cashback rate was 2.48%. Therefore, it is well worth keeping the card, as the Fidelity Rewards Visa Signature Card gives 2% cashback on all purchases, which is my opportunity cost.

However, my credit card usage was not optimal for several reasons. First, I shouldn’t have spent anything on “all other purchases”, which earns only 1%. This is because the definition of categories is sometimes unclear. For instance, I thought bakeries count as dining out (3%), and rideshares count as travel (3%), but that is not the case. For rideshares, I should use the American Express Blue Cash Preferred Card, as discussed here. Furthermore, I found that booking independent hotels sometimes does not trigger the 3% cashback on travel.

Second, 3% cashback on travel is not necessarily a good deal. Booking travel through the travel portals of American Express, Capital One, and Chase (using the corresponding cards) often gives you 5% cashback.

Third, since the 2% cashback rate on the Costco card is the same as with the Fidelity card, but the latter gives cashback every month, whereas the Costco card gives cashback only once a year, using the Fidelity card is better because we can earn more interest.

Therefore, based on my lifestyle, this card is most suitable for gas, EV charging, and dining out.

Although I like this card overall, the two features that I dislike are:

1. The credit card statement does not show how much cashback I earned through each transaction.
2. Cashback is applied only once a year.

In this sense, I prefer American Express because it is clear what we are earning, and we can redeem points or cashback anytime we want.

To provide context for how things unfolded, here is a summary of the timeline.

• November 2016: I purchased a Nissan Leaf.
• December 2022: The battery gauge lost 4 bars. I brought the vehicle to the dealer to have the battery replaced (covered under warranty), and the dealer told me it would take 20 weeks for the battery to arrive from Japan.
• Throughout 2023: There is no response from the Nissan dealer. I called them multiple times, but they always said they were still waiting.
• July 2023: I wrote this blog post.
• August 9, 2023: I contacted Nissan USA by web form to complain that Nissan (or the dealer) is not honoring the warranty and that I was ready to take legal action.
• August 10, 2023: Nissan acknowledges my complaint and forwards it to the Consumer Affairs Specialist.
• August 24, 2023: An Arbitration Specialist contacted me and mentioned that Nissan will offer to repurchase the vehicle, citing the Song-Beverly Consumer Warranty Act.
• August 31, 2023: I wrote this blog post.

The August 24 email requested that I send the bill of sale, pictures, and other documents, which I promptly did. Then on September 5, 2023, I received this repurchase offer. As mentioned in this post, I paid $42,647 for the vehicle, including everything, and the employer (UCSD) subsidized $10,000, leaving me to pay $32,647 out of pocket. Nissan offered $28,770 to repurchase this vehicle because they were either unable or unwilling to honor the battery warranty. But recall that I received $7,500 federal tax credit for purchasing an electric vehicle in 2016, so my actual cost was \(32647-7500=25147\). So, if this offer were true, it would mean I paid $25,147 for the vehicle, used it for 7 years, and sold it for $28,770.

It was crazy, but the deal was real. After carefully reviewing the contract, I signed it within a few hours, before Nissan could change their mind.

On September 28, 2023, I took the last picture of my Nissan Leaf before delivery. To be fair, it was a good car: quiet, easy to park, and with good acceleration, but the only and fatal issue was that battery degradation was too fast.

After delivering the vehicle and receiving the check, I went straight to the bank to cash it. I was delighted because this windfall temporarily alleviated my cash flow problem!