property tax check sent in December 2017 but not cashed until January 2018. Deductible?

You sent it in time for them to receive it and cash it before the end of the year, so you should be able to treat it as paid this year. The fact that they delayed isn't your problem.

*Neither*. If you mailed the check, the date the *post office* received the check is the date the payment is considered "paid" for tax purposes. *Proving* that date is a separate problem.

If I understand you, you're talking about a paper check sent via us postal Service. In that case, it doesn't matter when you mailed it or when they cashed it; the postmark is what matters. Presumably you mailed it in time to be postmarked in 2017.

I wonder if taxing authorities actually save envelopes, or images of them, in case of disputed postmarks. I played it safe and paid my early property taxes in person at the clerk's office, where I got a receipt.

I ALWAYS tell my clients that they should send any tax payment using certified mail. The extra few dollars is a cheap insurance policy should they ever need to prove a mailing date.

Ira Smilovitz, EA

To be on the safe side, you could have purchased a Certificate of Mailing for $1.35 as described here:

A certificate of mailing isn't sufficient. Although the USPS says it offers proof of mailing, the IRS explicitly states what they will accept as proof of mailing. Despite statements on the USPS website, the IRS does not include the USPS Certificate of Mailing as proof of mailing. (See 26 CFR 301.7502.1 for the relevant IRS regulation)

Ira Smilovitz, EA

The post office takes pictures of every envelope. You can sign up to get pix of your incoming mail via something called Informed Delivery. It's quite creepy.

But since I have no idea whether you can go back and ask for those pictures, don't waste money on certified mail and instead get a certificate of mailing, which is a little slip of paper (PS3817) with sender and recipient's address and a spot where the PO postmarks it.

A certificate of mailing is $1.35, certified mail is $3.35.

For the overeager, here's a printable PS3817 you can customize with your return address:

R's, John

As I stated in another reply, the certificate of mailing is not acceptable proof of mailing if you get into a dispute with the IRS. The regulation at 26 CFR 301.7502-1 is the only thing that matters.

Ira Smilovitz, EA

26 CFR 301.7502-1 applies to mailings to the IRS. It doesn't seem applicable to mailings to other organizations.

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Arthur L. Rubin, Brea, CA

By golly, you're right. Talk about the left hand not knowing what the right hand does.

R's, John

So, I got an email today from the tax collector's office saying my check arrived in their office on January 2. That would not have been possible if I had mailed it in 2018 since the Post Office is closed on January 1. Might this be enough?

I have never lied on my returns or been audited. I don't want to start now.

If the IRS chooses to question your deduction and sticks to the letter of the law/regulation, the email won't be sufficient proof. By not following the IRS instructions for establishing proof of mailing, there is a very small, but non-zero, risk that the deduction could be denied.

Ira Smilovitz, EA

The IRS rule you refer to pertains to payments made to the IRS. That is not what OP is asking about. Common sense should dictate in other cases. I doubt the IRS will be questioning the MILLIONS of December property tax payments made in 2017, and if they do taxpayers word and evidence such as mentioned by OP should suffice.

Taxed and Spent writes, above, that the IRS rule that Ira Smilovitz refers to pertains to payments made to the IRS.

T&S, can you show us where that rule is that says it refers only to payments to the IRS?

Read the definition of "payment" contained in that code section.

I don't disagree with you that the IRS is unlikely to do anything regarding 2017 RE tax payments, but the fact is, the IRS *could* do just that. Each year the IRS chooses where to focus its examination efforts. It may decide that Concepts like "should" are of little comfort if the IRS decides otherwise. Common sense and the tax code are not compatible concepts. It wouldn't take much effort for the IRS to program its computers to flag any return where RE tax claimed in 2017 is significantly greater than 2016, and generate a CP letter asking for more information. Again, I'm not suggesting the IRS will/would do this, but they could.

Ira Smilovitz, EA

There is no way the IRS would do that. They must realize that their success rate would be extremely low, and to send out CP letters to millions in the hope of catching a handful would really be rubbing SALT in the wounds.

With the current administration, anything is possible. The success rate is irrelevant. Since the CP letters are sent out without human intervention, there is nothing but taxpayer animosity to risk. The disagreement between the two of us is simply that you believe that common sense will prevail and I am trying to point out that if common sense fails there are real consequences. Deep down, I agree that common sense will prevail.

Ira Smilovitz, EA

Thank you all!!