Hearings, opened days after the 1974 attacks, were not continued after the jailing of six men, whose convictions were later quashed.
After the men's release in 1991 the families of those who died began a campaign to get the inquests heard.
Coroner Louise Hunt is expected to deliver her decision later.
Birmingham pub bombings inquests: What we know
A total of 182 people were also injured in the bombings, on 21 November 1974 - then the worst terrorist atrocity on English soil.
At 20:17 GMT, a device exploded in a duffel bag in the Mulberry Bush pub in the Rotunda, in the city centre, killing 10 people.
Pub bombers 'will not be jailed'
Ten minutes later, a second bomb went off in the Tavern in the Town, leaving 11 more dead.
The IRA was believed to have carried out the bombings, although responsibility has never been claimed.
West Midlands Police said the investigation is still open but there has not been enough evidence for a prosecution.
Ms Hunt, the Birmingham and Solihull coroner, has reviewed a huge body of police evidence and heard submissions from the victims' relatives and other interested parties in February.
She is expected to deliver her decision at Solihull Council house, during a hearing that is due to start at 10:00 BST.
Julie Hambleton, whose 18-year-old sister Maxine died in the attacks, said she was "cautiously optimistic" about the inquests resuming.

Right up till the close of Thursday's session, shares were not able to trade as there were about 10 times as many sell orders as there were bids.
According to the Tokyo Stock Exchange, the latest share price was indicated at 583 yen ($5.34; Â£3.74) a share.
That is a 20% plunge from the previous day close of 733 yen. Shares tanked by more than 15% on Wednesday.
That was as news emerged that Mitsubishi Motors had admitted falsifying fuel economy data for more than 600,000 vehicles sold in Japan. Officials have raided an office of Mitsubishi motors, and authorities are demanding a full report from the company, due on April 27th.
In the broader Japanese market, the benchmark Nikkei 225 index rose 2.7% - or 457.08 points - to close at 17,363.62. That is the highest level since 3 February.
More than 600,000
Japanese vehicles affected
157,000 Mitsubishi models
468,000 Nissan models
15% Wednesday's share price fall
"In a lot of respects I think yesterday's selling of Mitsubishi was a bit overdone," said Gavin Parry, managing director at Parry International Trading.
"From what we know so far it's all very domestic, with no US impact and no impact in Europe, and I think people are a bit hasty to cast this in the same light as the Volkswagen scandal. But of course the facts aren't all in yet, so it's hard to know for sure."
Mitsubishi's announcement follows on from the Volkswagen's emissions scandal last year, in which it was found to have cheated diesel emissions tests in the United States and elsewhere.
Elsewhere in Asia, China's Shanghai Composite index was up 0.42% at 2,985.12, while in Hong Kong the Hang Seng index rose 1.8% to 21,617.50.
In South Korea, the benchmark Kospi index closed up 0.8% at 2,022.10, while Australia's S&P ASX 200 index ended the day 1.1% higher at 5,272.69.
US stocks closed higher overnight amid mixed earnings reports. Coca Cola reported a fall in quarterly profit. Yahoo revealed a $99m loss in the first quarter. And chipmaker Intel announced it was cutting 11% of its workforce.
The Dow Jones closed up 42.67 points at 18,096.27, the S&P 500 added 1.60 points to 2,102.40 while the Nasdaq rose 3.35 points to 4,540.44.
A coroner is due to rule on whether the inquest into the deaths of 21 people in the Birmingham pub bombings will resume.
[NEXT_CONCEPT]
Investors in Tokyo are waiting in line to sell off more shares of Japanese automaker Mitsubishi Motors.