While we don't get to see 45*'s tax records right now, we can learn part of what we need to know by looking at the tiny sliver of information they do allow us to see.
It ain't sexy - it won't excite anybody outside a relatively small circle of Numbers Nerds - but this is how these things get done.
WaPo, David Herzig and Bridget Crawford
It’s possible the president filed the right paperwork. But without a full release of his tax returns, the available evidence suggests he hasn’t. According to New York City property records, Trump paid $13,000 in state and local transfer taxes for these two sales. That is the correct amount for a sale between strangers. But if he paid state and local transfer taxes, that means he didn’t treat the transfers as gifts. And on the real estate forms filed in New York, Trump didn’t check any of the boxes indicating that these were sales between relatives or sales of less than the entire property. It would seem, then, that he treated the transactions as if they were sales for fair market value to a stranger.
Since Trump did not cast the transactions as gifts for state and local tax purposes, it is almost certain that he did not do so for federal gift tax purposes, either. In our combined 40 years of experience as tax lawyers, we are unaware of a situation in which a taxpayer would report a transaction as a fair market value between strangers on the state level (and thus incur real estate taxes) but treat it as a gift at the federal level (and thus incur an additional tax). It’s fair to infer that Trump didn’t follow the rules.
And just in case you're looking for work in a field that's almost perfect for keeping you busy for decades to come as we try to unravel the shit blanket that's been thrown over our heads, it's worth considering a career in Forensic Accounting (yes - that's a thing). And if we're going to have any real chance to fix a tax system that's totally FUBAR, we'll be in dire need of some very good Numbers Nerds.