Perez was forced to miss the last two Formula 1 races at Silverstone after testing positive for COVID-19 shortly before the British Grand Prix.
The Mexican driver completed his required quarantine period in the UK, but remained positive for COVID-19 when tested ahead of the 70th Anniversary Grand Prix last weekend.
Racing Point now expects Perez to test negative for COVID-19 in the coming days, thus allowing him to return to his seat for the race weekend at the Circuit de Barcelona-Catalunya.
"It seems like the amount of virus in his system is coming down significantly from test to test," Racing Point team principal Otmar Szafnauer explained.
"He has tested again [on Saturday]. I anticipate either by the time we get the result, or we get a result early next week, he will be in the negative range.
"I think by the time we get to Barcelona, he'll be back in the car. But I'm trying to guess the future. If that doesn't happen, then don't crucify me because I can't predict the future.
"But just looking at the rate of the virus leaving his system, if it's linear, he should be OK by the time he gets back to Barcelona."
Perez was replaced at short-notice for the Silverstone races by Nico Hulkenberg, who made his F1 comeback with Racing Point after losing his Renault seat at the end of last year.
Asked if Hulkenberg would be on standby once again in Spain, Szafnauer said: "If [Perez] wasn't in the car, it would be Nico.
"I was 99% sure that Nico would be in the car for both Silverstones, and now 99% sure that Checo will be in the car for Spain."
Hulkenberg qualified third for the 70th Anniversary Grand Prix before finishing the race in seventh place, putting in a performance across the weekend that won praise from throughout the F1 paddock.
Hulkenberg said he was waiting to get clarification from Racing Point on if he would be needed for the Spanish Grand Prix weekend, but anticipated a late decision being made.
"I don't know the full picture to be honest yet," Hulkenberg said after the race. "I think we'll find out more in the next couple of days, and as we get closer to the weekend, it will develop.
"I guess I'll be present just in case he's not able to race. I guess I'll be there to replace him again. I think it will come down to again a late decision on Thursday."