I thought TIPS were essentially nothing more than T-bills, which pay almost nothing. If so, non-inflation of nothing doesn't really address the end goal: preserving your money's actual purchasing power. Does it?
TIPS are widely misunderstood, but really aren't all that complicated. Let me try to explain:
Scenario: I buy $100K worth of 20 year TIPS and $100K worth of 20 year treasury bonds on the auction at par. Each has a coupon. If inflation over the 20 years averages 2%, at maturity Treasury will pay me $148,590 on the TIPS and $100,000 on the bonds. The buying power of that $100K from the bonds has declined with inflation and is now $67,300. During the 20 years both the TIPS and the bonds have been paying their coupon rate.
Like anything, the bold print giveth and the fine print taketh away:
Takeaway #1: The IRS considers the increased value of the TIPS to be taxable income. Worse, it taxes each year's increase during the year. So if the TIPS are held in a taxable account, the holder ends up paying cash taxes annually on gains not physically received. Moral: TIPS are best held in tax-sheltered accounts.
Takeaway #2: TANSTAAFL. The coupon on the TIPS will be lower than the coupon on the bonds. Call the difference "the inflation insurance premium." We buy fire insurance on our house and pay an annual premium. In our opinion, the greatest financial risk to our retirement is unexpected high inflation (such as might occur with a significant dollar devaluation). So we also buy inflation insurance without paying a lot of attention to the actual cost of the premium.
Said in terms of formal risk management, we are looking at a high impact, low probability risk that is relatively inexpensive to mitigate. YMMV, of course.
Sort of Takeaway #3: There is also some fine print about what happens during an extended period of deflation, but that is not on my radar/not something I am worried about.
Regarding the government's creditworthiness I don't see any difference between TIPS and plain vanilla bonds. I also don't worry about it. If we do get a good shot of high inflation, though, Treasury will almost certainly stop selling TIPS, aka stop pouring gas on a fire. When/if that happens our TIPS will spike in value, bid up by panic-stricken buyers. It is possible that we will be able to take advantage of that.