During their bonding period, we’re told Lindsay and Charlie talked about everything — and at one point, Lindsay mentioned her ongoing tax problems.

We’re told Charlie offered to cut her a check then and there to get the IRS off her tail, but Lindsay refused.

Fast forward to last week — sources close to Lindsay tell TMZ, Lindsay’s biz manager received a check from Charlie for $100,000.

We’re told Lindsay was blown away by Charlie’s generosity — and immediately applied the money to her outstanding tax bill.

TMZ broke the story … Lindsay allegedly owed Uncle Sam $233,904 in unpaid taxes for 2009 and 2010 — but thanks to Charlie, that number’s nearly been cut in half.

As we reported, Lindsay’s slated to earn over $2 million the end of this year — but who knows where that’s going.

TMZ