A group of Senate Democrats on Thursday told Treasury Secretary Steven Mnuchin that they were worried the partial government shutdown would make it hard for taxpayers to receive assistance from the IRS during the upcoming filing season.

The senators raised concerns, specifically, that the shutdown led to the closure of the Taxpayer Advocate Service’s offices. The Taxpayer Advocate Service is an independent organization within the IRS that helps individuals and businesses with tax and filing issues.

{mosads}”The shutdown has closed every office of the Taxpayer Advocate Service across the country at a time when families and businesses are trying to determine the taxes that they owe and resolve disagreements with the IRS,” the senators said in a letter to Mnuchin.

Senate Finance Committee ranking member Ron Wyden (D-Ore.), and Finance Committee member Debbie Stabenow (D-Mich.), took the lead on the letter.

The IRS has received considerable attention from politicians during the shutdown. There were concerns that the agency wouldn’t be able to issue refunds during the shutdown, but the Trump administration announced earlier this week that refunds would be paid if the shutdown persists into the filing season. 

The IRS said the filing season would begin on Jan. 28 and that some furloughed employees would be called back to work during that time. The agency is expected to release a filing-season shutdown contingency plan in the near future.

Democrats remain concerned that taxpayers will have challenges during the filing season even if refunds are issued.

“Taxpayers should receive their refunds in a timely manner, but taxpayers should also receive the necessary assistance to ensure that they are filing their taxes correctly and that they have advocates working on their behalf,” the Senate Democrats wrote in their letter.

The senators asked Mnuchin if Taxpayer Advocate Service employees will be asked to come back to work in the shutdown plan for the forthcoming filing season. They also asked Mnuchin how Treasury plans to help taxpayers who face financial difficulties resulting from challenges filing their taxes or getting their refunds amid the shutdown. 

The House passed legislation Wednesday to fund the agency in a 240-188 vote, with eight Republicans bucking party lines to back the bill. But the White House has threatened to veto the bill because there’s no agreement “to address the border crisis.”

The government entered a partial shutdown on Dec. 22 amid an impasse between lawmakers and the White House over President Trump’s demand for $5.7 billion in border wall funding.