Former President Donald J. Trump has spent more than $100 million since leaving office, on lawyers and other costs related to fending off various investigations, indictments and his coming criminal trials, according to a New York Times review of federal records.

The remarkable sum means that Mr. Trump has averaged more than $90,000 a day in legal-related costs for more than three years — none of it paid for with his own money.

Instead, the former president has relied almost entirely on donations made in an attempt to fight the results of the 2020 election.

Now, those accounts are nearly drained, and Mr. Trump faces a choice: begin to pay his own substantial legal fees or find another way to finance them.

November 2020 to Early 2021

Mr. Trump raised a staggering $254 million online from Nov. 4, 2020, the day after the election, to President Biden’s inauguration on Jan. 20, 2021, as he urged supporters to fuel an “election defense fund.”

The contributions came so quickly that on Nov. 9, Mr. Trump formed a new political action committee, Save America, to store all the cash.

Only a fraction of the money, however, went toward recounts and other legal challenges to the election. Some went to Mr. Trump’s lawyers during his second impeachment, related to the Jan. 6 riot.

But Mr. Trump banked much of the cash.

Rest of 2021

Mr. Trump started to use the money to fund his post-presidential political operation and what would eventually become his sprawling legal teams. In February, Trump renamed his 2020 committee to “MAGA PAC.”

By the end of 2021, Save America, which continued to bring in new donations, held a substantial portion of Mr. Trump’s fund-raising: $105 million.

2022

Both Save America and MAGA PAC spent significantly in 2022 on legal bills and other related expenses. The House held its impeachment hearings. The F.B.I. searched Mar-a-Lago for missing classified documents in August. Mr. Trump’s legal fees rose.

Mr. Trump spent about $27.2 million on legal-related costs for the year.

As Mr. Trump prepared to announce his 2024 run late in 2022, he faced a quandary: His PAC could not directly spend money to elect him as president. So Save America transferred $60 million to a pro-Trump super PAC called MAGA Inc.

2023

Save America began 2023 with $18.3 million. But Mr. Trump’s legal expenses were about to soar. He was first indicted in March 2023 in New York. Three other indictments followed.

Mr. Trump spent close to $60 million on legal and investigation-related costs — which included his lawyers, a document-production company and an expert witness in Trump’s New York civil fraud case.

Early last year, Mr. Trump made a change to bring more money into Save America, the PAC that was paying his legal expenses. At first, one cent of every dollar he raised online went to Save America; the rest went to his 2024 campaign. But with Save America short of cash to pay lawyers, he increased that to 10 percent.

It was still not enough. By June 2023, Save America had less than $4 million on hand. In an unusual move, Mr. Trump asked his super PAC for a refund of the $60 million he had given just months earlier, so that Save America could continue paying for his legal expenses.

By the end of 2023, more than $42 million had been returned from his super PAC to Save America.

2024

With his first trial looming — in the New York case related to hush-money payments to a porn star in 2016 — Mr. Trump’s legal costs continued to rise. He spent at least $9.7 million in January and February.

The more than $100 million in legal spending since leaving office does not include spending from Mr. Trump’s 2024 campaign, which has not paid for his personal legal bills.

To cover the ongoing legal costs, his super PAC refunded an additional $10 million in January and February. But there is now only $7.75 million left to refund. Save America had less than $4 million at the end of February, when accounting for unpaid debts.

The Trump team has said the Republican National Committee won’t pay his legal bills. But his new shared fund-raising agreement with the party directs a portion of donations to his Save America PAC before the party itself.

Still, the account paying Mr. Trump’s legal bills will most likely be out of money by summer at the current spending pace.

Then, Mr. Trump will have to decide: Whose money will he use to pay his lawyers?