Tax rate parity for married filing single and single filers ends in the 25% bracket at around $75k of income for each individual. Just math but to be “double digit” — i.e., $10k or more “short” at return filing time either puts you at a substantially higher income position than the $75k per head, or just flat out failing to get your withholding anywhere near the ballpark.
Not to be “judgy” but sounds like not too bad of a problem to have from a pure income perspective. Suggest taking a hard look at your withholding or making quarterly estimated payments to avoid penalties, interest, and general April shock.
Not sure about your facts but it gets trickier forecasting tax liability when you add self employment/freelancing revenue to the mix, or other forms of lumpy income (but it doesn’t sound like that’s the case since the advice was for you to start a business to burn cash).
Hope the vacation did the trick!
Anyway. Not tax advice. Just hypos. Circ. 230, all that.